在Flood Paint游戏中，游戏的目标是在尽可能少的回合时间内使整个板成为相同的颜色。

游戏从一个看起来像这样的棋盘开始：

3 3 5 4 1 3 4 1 5
5 1 3 4 1 1 5 2 1
6 5 2 3 4 3 3 4 3
4 4 4 5 5 5 4 1 4
6 2 5 3[3]1 1 6 6
5 5 1 2 5 2 6 6 3
6 1 1 5 3 6 2 3 6
1 2 2 4 5 3 5 1 2
3 6 6 1 5 1 3 2 4

当前，板中心的数字（代表颜色）为3。每转一圈，中心的正方形将改变颜色，并且可以通过水平或垂直移动从中心到达的所有相同颜色的正方形（即在中心广场的泛滥区域）将随之改变颜色。因此，如果中心方块将颜色更改为5：

3 3 5 4 1 3 4 1 5
5 1 3 4 1 1 5 2 1
6 5 2 3 4 3 3 4 3
4 4 4 5 5 5 4 1 4
6 2 5 5[5]1 1 6 6
5 5 1 2 5 2 6 6 3
6 1 1 5 3 6 2 3 6
1 2 2 4 5 3 5 1 2
3 6 6 1 5 1 3 2 4

那么位于中心3左侧的3也将更改颜色。现在，从中间一个可以到达七个5，因此如果我们将颜色更改为4：

3 3 5 4 1 3 4 1 5
5 1 3 4 1 1 5 2 1
6 5 2 3 4 3 3 4 3
4 4 4 4 4 4 4 1 4
6 2 4 4[4]1 1 6 6
5 5 1 2 4 2 6 6 3
6 1 1 5 3 6 2 3 6
1 2 2 4 5 3 5 1 2
3 6 6 1 5 1 3 2 4

绘制区域的大小再次急剧增加。

您的任务是创建一个程序，该程序将以19到19的1到6的颜色网格作为输入，以您选择的任何形式：

4 5 1 1 2 2 1 6 2 6 3 4 2 3 2 3 1 6 3
4 2 6 3 4 4 5 6 4 4 5 3 3 3 3 5 4 3 4
2 3 5 2 2 5 5 1 2 6 2 6 6 2 1 6 6 1 2
4 6 5 5 5 5 4 1 6 6 3 2 6 4 2 6 3 6 6
1 6 4 4 4 4 6 4 2 5 5 3 2 2 4 1 5 2 5
1 6 2 1 5 1 6 4 4 1 5 1 3 4 5 2 3 4 1
3 3 5 3 2 2 2 4 2 1 6 6 6 6 1 4 5 2 5
1 6 1 3 2 4 1 3 3 4 6 5 1 5 5 3 4 3 3
4 4 1 5 5 1 4 6 3 3 4 5 5 6 1 6 2 6 4
1 4 2 5 6 5 5 3 2 5 5 5 3 6 1 4 4 6 6
4 6 6 2 6 6 2 4 2 6 1 5 6 2 3 3 4 3 6
6 1 3 6 3 5 5 3 6 1 3 4 4 5 1 2 6 4 3
2 6 1 3 2 4 2 6 1 1 5 2 6 6 6 6 3 3 3
3 4 5 4 6 6 3 3 4 1 1 6 4 5 1 3 4 1 2
4 2 6 4 1 5 3 6 4 3 4 5 4 2 1 1 4 1 1
4 2 4 1 5 2 2 3 6 6 6 5 2 5 4 5 4 5 1
5 6 2 3 4 6 5 4 1 3 2 3 2 1 3 6 2 2 4
6 5 4 1 3 2 2 1 1 1 6 1 2 6 2 5 6 4 5
5 1 1 4 2 6 2 5 6 1 3 3 4 1 6 1 2 1 2

然后以您选择的格式返回一系列颜色，以使中心方块每次旋转都会改变：

263142421236425431645152623645465646213545631465

在每个移动序列的末尾，19 x 19网格中的正方形必须全部具有相同的颜色。

您的程序必须完全具有确定性。允许使用伪随机解，但是程序每次必须为相同的测试用例生成相同的输出。

获胜的程序将以最少的步骤总数来解决此文件（压缩文本文件，14.23 MB）中找到的所有100,000个测试用例。如果两个解决方案采用相同数量的步骤（例如，如果它们都找到了最佳策略），则较短的程序将获胜。

BurntPizza用Java编写了一个程序来验证测试结果。要使用此程序，请运行您的提交并将输出通过管道传输到名为的文件中steps.txt。然后，使用steps.txt和floodtest文件在同一目录中运行该程序。如果您输入的内容有效并为所有文件提供了正确的解决方案，则应通过所有测试并返回All boards solved successfully.

import java.io.*;
import java.util.*;

public class PainterVerifier {

    public static void main(String[] args) throws FileNotFoundException {

        char[] board = new char[361];

        Scanner s = new Scanner(new File("steps.txt"));
        Scanner b = new Scanner(new File("floodtest"));

        int lineNum = 0;

        caseloop: while (b.hasNextLine()) {

            for (int l = 0; l < 19; l++) {
                String lineb = b.nextLine();
                if (lineb.isEmpty())
                    continue caseloop;
                System.arraycopy(lineb.toCharArray(), 0, board, l * 19, 19);
            }

            String line = s.nextLine();
            if (line.isEmpty())
                continue;
            char[] steps = line.toCharArray();

            Stack<Integer> nodes = new Stack<Integer>();

            for (char c : steps) {
                char targetColor = board[180];
                char replacementColor = c;

                nodes.push(180);

                while (!nodes.empty()) {
                    int n = nodes.pop();
                    if (n < 0 || n > 360)
                        continue;
                    if (board[n] == targetColor) {
                        board[n] = replacementColor;
                        if (n % 19 > 0)
                            nodes.push(n - 1);
                        if (n % 19 < 18)
                            nodes.push(n + 1);
                        if (n / 19 > 0)
                            nodes.push(n - 19);
                        if (n / 19 < 18)
                            nodes.push(n + 19);
                    }
                }
            }
            char center = board[180];
            for (char c : board)
                if (c != center) {
                    s.close();
                    b.close();

                    System.out.println("\nIncomplete board found!\n\tOn line " + lineNum + " of steps.txt");
                    System.exit(0);
                }

            if (lineNum % 5000 == 0)
                System.out.printf("Verification %d%c complete...\n", lineNum * 100 / 100000, '%');

            lineNum++;
        }
        s.close();
        b.close();
        System.out.println("All boards solved successfully.");
    }
}

另外，是一个记分板，因为结果实际上不是按分数排序的，因此在这里实际上很重要：

1. 1,985,078 -smack42，Java
2. 2,075,452 -user1502040，C
3. 2,098,382 -tigrou，C＃
4. 2,155,834 -CoderTao，C＃
5. 2,201,995 -Java的MrBackend
6. 2,383,569 -CoderTao，C＃
7. 2,384,020 -Herjan，C
8. 2,403,189 -Origineil，Java
9. 2,445,761 -Herjan，C
10. 2,475,056 -Jeremy List，Haskell
11. 2,480,714 -SteelTermite，C（2,395字节）
12. 2,480,714 -Java的Herjan（4,702字节）
13. 2,588,847 -BurntPizza，Java（2,748字节）
14. 2,588,847 -Gero3，node.js（4,641字节）
15. 2,979,145-德尔福XE3的Teun Pronk
16. 4,780,841 -BurntPizza，Java
17. 10,800,000 -Joe Z.，Python

Java-1,985,078步

https://github.com/smack42/ColorFill

另一个迟到的条目。包含1,985,078个步骤的结果文件可以在此处找到。

一些背景信息：

几年前，当我开始编写自己的Flood-it游戏副本时，我发现了这一挑战。

“最好的不完整” DFS和A *算法
从一开始，我就想为这款游戏创建一个好的解算器算法。随着时间的流逝，我可以通过包含几种进行不同不完全搜索的策略（类似于此处其他程序中使用的策略）并对每个解决方案使用这些策略的最佳结果来改进我的求解器。我什至用Java 重新实现了tigrou的A *算法，并将其添加到我的求解器中，以获得比tigrou的结果更好的整体解决方案。

详尽的DFS算法
然后，我专注于始终寻找最佳解决方案的算法。我花了很多精力来优化详尽的深度优先搜索策略。为了加快搜索速度，我添加了一个哈希表来存储所有探索的状态，以便搜索可以避免再次探索它们。尽管此算法可以很好地工作，并且可以足够快地解决所有14x14难题，但是在此代码挑战中，它占用了太多内存并且在19x19难题中运行非常缓慢。

Puchert A *算法
几个月前，Aaron和Simon Puchert与我联系，讨论了Flood-It解算器。该程序使用具有允许的试探性的A *型算法（与tigrou的算法相反），并且移动修剪与跳转点搜索类似。我很快注意到该程序非常快，并且找到了最佳解决方案！

当然，我必须重新实现这个出色的算法并将其添加到我的程序中。我努力优化Java程序，使其运行速度与Puchert兄弟的原始C ++程序一样快。然后，我决定尝试这个挑战的100,000个测试案例。在我的机器上，该程序使用我的Puchert A *算法实现，运行了120多个小时以找到1,985,078个步骤。

这是最好的解决方案这一挑战，除非有这将导致次优解决方案，该方案的一些错误。欢迎任何反馈！

编辑：在此处添加了代码的相关部分：

AStarPuchertStrategy类

/**
 * a specific strategy for the AStar (A*) solver.
 * <p>
 * the idea is taken from the program "floodit" by Aaron and Simon Puchert,
 * which can be found at <a>https://github.com/aaronpuchert/floodit</a>
 */
public class AStarPuchertStrategy implements AStarStrategy {

    private final Board board;
    private final ColorAreaSet visited;
    private ColorAreaSet current, next;
    private final short[] numCaNotFilledInitial;
    private final short[] numCaNotFilled;

    public AStarPuchertStrategy(final Board board) {
        this.board = board;
        this.visited = new ColorAreaSet(board);
        this.current = new ColorAreaSet(board);
        this.next = new ColorAreaSet(board);
        this.numCaNotFilledInitial = new short[board.getNumColors()];
        for (final ColorArea ca : board.getColorAreasArray()) {
            ++this.numCaNotFilledInitial[ca.getColor()];
        }
        this.numCaNotFilled = new short[board.getNumColors()];
    }

    /* (non-Javadoc)
     * @see colorfill.solver.AStarStrategy#setEstimatedCost(colorfill.solver.AStarNode)
     */
    @Override
    public void setEstimatedCost(final AStarNode node) {

        // quote from floodit.cpp: int State::computeValuation()
        // (in branch "performance")
        //
        // We compute an admissible heuristic recursively: If there are no nodes
        // left, return 0. Furthermore, if a color can be eliminated in one move
        // from the current position, that move is an optimal move and we can
        // simply use it. Otherwise, all moves fill a subset of the neighbors of
        // the filled nodes. Thus, filling that layer gets us at least one step
        // closer to the end.

        node.copyFloodedTo(this.visited);
        System.arraycopy(this.numCaNotFilledInitial, 0, this.numCaNotFilled, 0, this.numCaNotFilledInitial.length);
        {
            final ColorAreaSet.FastIteratorColorAreaId iter = this.visited.fastIteratorColorAreaId();
            int nextId;
            while ((nextId = iter.nextOrNegative()) >= 0) {
                --this.numCaNotFilled[this.board.getColor4Id(nextId)];
            }
        }

        // visit the first layer of neighbors, which is never empty, i.e. the puzzle is not solved yet
        node.copyNeighborsTo(this.current);
        this.visited.addAll(this.current);
        int completedColors = 0;
        {
            final ColorAreaSet.FastIteratorColorAreaId iter = this.current.fastIteratorColorAreaId();
            int nextId;
            while ((nextId = iter.nextOrNegative()) >= 0) {
                final byte nextColor = this.board.getColor4Id(nextId);
                if (--this.numCaNotFilled[nextColor] == 0) {
                    completedColors |= 1 << nextColor;
                }
            }
        }
        int distance = 1;

        while(!this.current.isEmpty()) {
            this.next.clear();
            final ColorAreaSet.FastIteratorColorAreaId iter = this.current.fastIteratorColorAreaId();
            int thisCaId;
            if (0 != completedColors) {
                // We can eliminate colors. Do just that.
                // We also combine all these elimination moves.
                distance += Integer.bitCount(completedColors);
                final int prevCompletedColors = completedColors;
                completedColors = 0;
                while ((thisCaId = iter.nextOrNegative()) >= 0) {
                    final ColorArea thisCa = this.board.getColorArea4Id(thisCaId);
                    if ((prevCompletedColors & (1 << thisCa.getColor())) != 0) {
                        // completed color
                        // expandNode()
                        for (final int nextCaId : thisCa.getNeighborsIdArray()) {
                            if (!this.visited.contains(nextCaId)) {
                                this.visited.add(nextCaId);
                                this.next.add(nextCaId);
                                final byte nextColor = this.board.getColor4Id(nextCaId);
                                if (--this.numCaNotFilled[nextColor] == 0) {
                                    completedColors |= 1 << nextColor;
                                }
                            }
                        }
                    } else {
                        // non-completed color
                        // move node to next layer
                        this.next.add(thisCaId);
                    }
                }
            } else {
                // Nothing found, do the color-blind pseudo-move
                // Expand current layer of nodes.
                ++distance;
                while ((thisCaId = iter.nextOrNegative()) >= 0) {
                    final ColorArea thisCa = this.board.getColorArea4Id(thisCaId);
                    // expandNode()
                    for (final int nextCaId : thisCa.getNeighborsIdArray()) {
                        if (!this.visited.contains(nextCaId)) {
                            this.visited.add(nextCaId);
                            this.next.add(nextCaId);
                            final byte nextColor = this.board.getColor4Id(nextCaId);
                            if (--this.numCaNotFilled[nextColor] == 0) {
                                completedColors |= 1 << nextColor;
                            }
                        }
                    }
                }
            }

            // Move the next layer into the current.
            final ColorAreaSet tmp = this.current;
            this.current = this.next;
            this.next = tmp;
        }
        node.setEstimatedCost(node.getSolutionSize() + distance);
    }

}

AStarSolver类的一部分

private void executeInternalPuchert(final ColorArea startCa) throws InterruptedException {
    final Queue<AStarNode> open = new PriorityQueue<AStarNode>(AStarNode.strongerComparator());
    open.offer(new AStarNode(this.board, startCa));
    AStarNode recycleNode = null;
    while (open.size() > 0) {
        if (Thread.interrupted()) { throw new InterruptedException(); }
        final AStarNode currentNode = open.poll();
        if (currentNode.isSolved()) {
            this.addSolution(currentNode.getSolution());
            return;
        } else {
            // play all possible colors
            int nextColors = currentNode.getNeighborColors(this.board);
            while (0 != nextColors) {
                final int l1b = nextColors & -nextColors; // Integer.lowestOneBit()
                final int clz = Integer.numberOfLeadingZeros(l1b); // hopefully an intrinsic function using instruction BSR / LZCNT / CLZ
                nextColors ^= l1b; // clear lowest one bit
                final byte color = (byte)(31 - clz);
                final AStarNode nextNode = currentNode.copyAndPlay(color, recycleNode, this.board);
                if (null != nextNode) {
                    recycleNode = null;
                    this.strategy.setEstimatedCost(nextNode);
                    open.offer(nextNode);
                }
            }
        }
        recycleNode = currentNode;
    }
}

类AStarNode的一部分

/**
 * check if this color can be played. (avoid duplicate moves)
 * the idea is taken from the program "floodit" by Aaron and Simon Puchert,
 * which can be found at <a>https://github.com/aaronpuchert/floodit</a>
 * @param nextColor
 * @return
 */
private boolean canPlay(final byte nextColor, final List<ColorArea> nextColorNeighbors) {
    final byte currColor = this.solution[this.solutionSize];
    // did the previous move add any new "nextColor" neighbors?
    boolean newNext = false;
next:   for (final ColorArea nextColorNeighbor : nextColorNeighbors) {
        for (final ColorArea prevNeighbor : nextColorNeighbor.getNeighborsArray()) {
            if ((prevNeighbor.getColor() != currColor) && this.flooded.contains(prevNeighbor)) {
                continue next;
            }
        }
        newNext = true;
        break next;
    }
    if (!newNext) {
        if (nextColor < currColor) {
            return false;
        } else {
            // should nextColor have been played before currColor?
            for (final ColorArea nextColorNeighbor : nextColorNeighbors) {
                for (final ColorArea prevNeighbor : nextColorNeighbor.getNeighborsArray()) {
                    if ((prevNeighbor.getColor() == currColor) && !this.flooded.contains(prevNeighbor)) {
                        return false;
                    }
                }
            }
            return true;
        }
    } else {
        return true;
    }
}

/**
 * try to re-use the given node or create a new one
 * and then play the given color in the result node.
 * @param nextColor
 * @param recycleNode
 * @return
 */
public AStarNode copyAndPlay(final byte nextColor, final AStarNode recycleNode, final Board board) {
    final List<ColorArea> nextColorNeighbors = new ArrayList<ColorArea>(128);  // constant, arbitrary initial capacity
    final ColorAreaSet.FastIteratorColorAreaId iter = this.neighbors.fastIteratorColorAreaId();
    int nextId;
    while ((nextId = iter.nextOrNegative()) >= 0) {
        final ColorArea nextColorNeighbor = board.getColorArea4Id(nextId);
        if (nextColorNeighbor.getColor() == nextColor) {
            nextColorNeighbors.add(nextColorNeighbor);
        }
    }
    if (!this.canPlay(nextColor, nextColorNeighbors)) {
        return null;
    } else {
        final AStarNode result;
        if (null == recycleNode) {
            result = new AStarNode(this);
        } else {
            // copy - compare copy constructor
            result = recycleNode;
            result.flooded.copyFrom(this.flooded);
            result.neighbors.copyFrom(this.neighbors);
            System.arraycopy(this.solution, 0, result.solution, 0, this.solutionSize + 1);
            result.solutionSize = this.solutionSize;
            //result.estimatedCost = this.estimatedCost;  // not necessary to copy
        }
        // play - compare method play()
        for (final ColorArea nextColorNeighbor : nextColorNeighbors) {
            result.flooded.add(nextColorNeighbor);
            result.neighbors.addAll(nextColorNeighbor.getNeighborsIdArray());
        }
        result.neighbors.removeAll(result.flooded);
        result.solution[++result.solutionSize] = nextColor;
        return result;
    }
}

C＃-2,098,382个步骤

我尝试了很多事情，其中​​大多数失败了，直到最近才完全失效。我得到了足够有趣的东西来发表答案。

当然，有很多方法可以进一步改善这一点。我认为按照2M的步骤进行操作是可能的。

大约花费了时间7 hours才能产生结果。这是包含所有解决方案的txt文件，以防万一有人要检查它们：results.zip

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;

namespace FloodPaintAI
{
    class Node
    {   
        public byte Value;             //1-6
        public int Index;              //unique identifier, used for easily deepcopying the graph
        public List<Node> Neighbours;  
        public List<Tuple<int, int>> NeighboursPositions; //used by BuildGraph() 

        public int Depth;    //used by GetSumDistances() 
        public bool Checked; // 

        public Node(byte value, int index)
        {
            Value = value;      
            Index = index;          
        }

        public Node(Node node)
        {           
            Value = node.Value; 
            Index = node.Index;                     
        }
    }

    class Board
    {
        private const int SIZE = 19;
        private const int STARTPOSITION = 9;

        public Node Root;         //root of graph. each node is a set of contiguous, same color square
        public List<Node> Nodes;  //all nodes in the graph, used for deep copying


        public int EstimatedCost; //estimated cost, used by A* Pathfinding
        public List<byte> Solution;

        public Board(StreamReader input)
        {                   
            byte[,] board = new byte[SIZE, SIZE];
            for(int j = 0 ; j < SIZE ; j++)
            {
                string line = input.ReadLine();
                for(int i = 0 ; i < SIZE ; i++)         
                {                                       
                    board[j, i] = byte.Parse(line[i].ToString());
                }               
            }
            Solution = new List<byte>();
            BuildGraph(board);  
        }

        public Board(Board boardToCopy)
        {               
            //copy the graph            
            Nodes = new List<Node>(boardToCopy.Nodes.Count);
            foreach(Node nodeToCopy in boardToCopy.Nodes)
            {
                Node node = new Node(nodeToCopy);
                Nodes.Add(node);
            }

            //copy "Neighbours" property
            for(int i = 0 ; i < boardToCopy.Nodes.Count ; i++)
            {
                Node node = Nodes[i];
                Node nodeToCopy = boardToCopy.Nodes[i];

                node.Neighbours = new List<Node>(nodeToCopy.Neighbours.Count);
                foreach(Node neighbour in nodeToCopy.Neighbours)
                {
                    node.Neighbours.Add(Nodes[neighbour.Index]);
                }
            }

            Root = Nodes[boardToCopy.Root.Index];
            EstimatedCost = boardToCopy.EstimatedCost;          
            Solution = new List<byte>(boardToCopy.Solution);            
        }

        private void BuildGraph(byte[,] board)
        {                       
            int[,] nodeIndexes = new int[SIZE, SIZE];
            Nodes = new List<Node>();

            //check how much sets we have (1st pass)
            for(int j = 0 ; j < SIZE ; j++)
            {
                for(int i = 0 ; i < SIZE ; i++)         
                {               
                    if(nodeIndexes[j, i] == 0) //not already visited                    
                    {
                        Node newNode = new Node(board[j, i], Nodes.Count);                      
                        newNode.NeighboursPositions = new List<Tuple<int, int>>();
                        Nodes.Add(newNode);

                        BuildGraphFloodFill(board, nodeIndexes, newNode, i, j, board[j, i]);
                    }
                }       
            }

            //set neighbours and root (2nd pass)
            foreach(Node node in Nodes)
            {
                node.Neighbours = new List<Node>();
                node.Neighbours.AddRange(node.NeighboursPositions.Select(x => nodeIndexes[x.Item2, x.Item1]).Distinct().Select(x => Nodes[x - 1]));
                node.NeighboursPositions = null;                
            }
            Root = Nodes[nodeIndexes[STARTPOSITION, STARTPOSITION] - 1];            
        }

        private void BuildGraphFloodFill(byte[,] board, int[,] nodeIndexes, Node node, int startx, int starty, byte floodvalue)
        {
            Queue<Tuple<int, int>> queue = new Queue<Tuple<int, int>>();
            queue.Enqueue(new Tuple<int, int>(startx, starty));

            while(queue.Count > 0)
            {
                Tuple<int, int> position = queue.Dequeue();
                int x = position.Item1;
                int y = position.Item2;

                if(x >= 0 && x < SIZE && y >= 0 && y < SIZE)
                {
                    if(nodeIndexes[y, x] == 0 && board[y, x] == floodvalue)
                    {
                        nodeIndexes[y, x] = node.Index + 1;

                        queue.Enqueue(new Tuple<int, int>(x + 1, y));
                        queue.Enqueue(new Tuple<int, int>(x - 1, y));
                        queue.Enqueue(new Tuple<int, int>(x, y + 1));
                        queue.Enqueue(new Tuple<int, int>(x, y - 1));                                           
                    }               
                    if(board[y, x] != floodvalue)
                        node.NeighboursPositions.Add(position);                         
                }       
            }
        }

        public int GetEstimatedCost()
        {       
            Board current = this;

            //copy current board and play the best color until the end.
            //number of moves required to go the end is the heuristic
            //estimated cost = current cost + heuristic
            while(!current.IsSolved())
            {
                int minSumDistance = int.MaxValue;
                Board minBoard = null;

                //find color which give the minimum sum of distance from root to each other node
                foreach(byte i in current.Root.Neighbours.Select(x => x.Value).Distinct())
                {
                    Board copy = new Board(current);
                    copy.Play(i);                   

                    int distance = copy.GetSumDistances();                  

                    if(distance < minSumDistance)
                    {
                        minSumDistance = distance;
                        minBoard = copy;
                    }
                }
                current = minBoard;
            }           
            return current.Solution.Count;
        }

        public int GetSumDistances()
        {
            //get sum of distances from root to each other node, using BFS
            int sumDistances = 0;           

            //reset marker
            foreach(Node n in Nodes)
            {
                n.Checked = false;                                  
            }

            Queue<Node> queue = new Queue<Node>();
            Root.Checked = true;
            Root.Depth = 0; 
            queue.Enqueue(Root);

            while(queue.Count > 0)
            {
                Node current = queue.Dequeue();                             
                foreach(Node n in current.Neighbours)
                {
                    if(!n.Checked)          
                    {                                   
                        n.Checked = true;                                               
                        n.Depth = current.Depth + 1;
                        sumDistances += n.Depth;            
                        queue.Enqueue(n);   
                    }               
                }
            }
            return sumDistances;
        }       

        public void Play(byte value)            
        {
            //merge root node with other neighbours nodes, if color is matching
            Root.Value = value;
            List<Node> neighboursToRemove = Root.Neighbours.Where(x => x.Value == value).ToList();
            List<Node> neighboursToAdd = neighboursToRemove.SelectMany(x => x.Neighbours).Except((new Node[] { Root }).Concat(Root.Neighbours)).ToList();

            foreach(Node n in neighboursToRemove)
            {
                foreach(Node m in n.Neighbours)
                {
                    m.Neighbours.Remove(n);
                }
                Nodes.Remove(n);
            }   

            foreach(Node n in neighboursToAdd)
            {
                Root.Neighbours.Add(n);         
                n.Neighbours.Add(Root); 
            }           

            //re-synchronize node index
            for(int i = 0 ; i < Nodes.Count ; i++)
            {
                Nodes[i].Index = i;
            }           
            Solution.Add(value);
        }

        public bool IsSolved()
        {           
            //return Nodes.Count == 1;
            return Root.Neighbours.Count == 0;  
        }           
    }


    class Program
    {       
        public static List<byte> Solve(Board input)
        {
            //A* Pathfinding            
            LinkedList<Board> open = new LinkedList<Board>();       
            input.EstimatedCost = input.GetEstimatedCost();
            open.AddLast(input);            

            while(open.Count > 0)
            {                       
                Board current = open.First.Value;
                open.RemoveFirst();

                if(current.IsSolved())
                {
                    return current.Solution;                
                }
                else
                {
                    //play all neighbours nodes colors
                    foreach(byte i in current.Root.Neighbours.Select(x => x.Value).Distinct())
                    {                       
                        Board newBoard = new Board(current);
                        newBoard.Play(i);           
                        newBoard.EstimatedCost = newBoard.GetEstimatedCost();   

                        //insert board to open list
                        bool inserted = false;
                        for(LinkedListNode<Board> node = open.First ; node != null ; node = node.Next)
                        {                               
                            if(node.Value.EstimatedCost > newBoard.EstimatedCost)
                            {
                                open.AddBefore(node, newBoard);
                                inserted = true;
                                break;
                            }
                        }       
                        if(!inserted)
                            open.AddLast(newBoard);                                                 
                    }   
                }   
            }
            throw new Exception(); //no solution found, impossible
        }   

        public static void Main(string[] args)
        {                   
            using (StreamReader sr = new StreamReader("floodtest"))
            {   
                while(!sr.EndOfStream)
                {                               
                    List<Board> boards = new List<Board>();
                    while(!sr.EndOfStream && boards.Count < 100)
                    {
                        Board board = new Board(sr);                        
                        sr.ReadLine(); //skip empty line
                        boards.Add(board);
                    }                                           
                    List<byte>[] solutions = new List<byte>[boards.Count];                                          
                    Parallel.For(0, boards.Count, i => 
                    {                               
                        solutions[i] = Solve(boards[i]); 
                    });                                         
                    foreach(List<byte> solution in solutions)
                    {
                        Console.WriteLine(string.Join(string.Empty, solution));                                             
                    }       
                }               
            }
        }
    }
}

有关其工作原理的更多详细信息：

它使用A *寻路算法。

很难找到一个好东西heuristic。如果heuristic它低估了成本，它的性能几乎与Dijkstra算法相似，并且由于具有6种颜色的19x19电路板的复杂性，它将永远运行。如果它高估了成本，它将迅速收敛到一个解决方案，但根本不会给出好的解决方案（比如说有26举动可能是19的举动）。找到heuristic能够给出解决方案的确切剩余步骤数的最佳方法是最好的（这将是快速的，并且将给出可能的最佳解决方案）。这是不可能的（除非我错了）。实际上，这实际上需要首先解决电路板本身，而这实际上是您要尝试做的（鸡肉和鸡蛋问题）

我尝试了很多事情，这是对heuristic：

• 我建立了当前董事会的图表进行评估。每个node代表一组连续的相同颜色的正方形。使用该graph函数，我可以轻松计算出中心到任何其他节点的确切最小距离。例如，从中心到左上的距离为10，因为至少有10种颜色将它们分开。
• 为了进行计算heuristic：我将当前板演奏到最后。对于每个步骤，我选择一种颜色，该颜色将使从根到所有其他节点的距离之和最小。

• 要达到此目的所需的移动次数是heuristic。

• Estimated cost（由A *使用）= moves so far+heuristic

它不是完美的，因为它稍微高估了成本（因此找到了非最优的解决方案）。无论如何，它是快速计算并给出良好结果的方法。

通过使用图形执行所有操作，我可以极大地提高速度。一开始我有一个2-dimension数组。我将其淹没并在需要时重新计算图形（例如：计算启发式）。现在，所有操作都使用该图完成，该图仅在开始时计算。为了模拟步骤，不再需要泛洪填充，而是合并节点。这快很多。

Python – 10,800,000步

作为最后的参考解决方案，请考虑以下顺序：

print "123456" * 18

循环遍历所有颜色n时间，这意味着n距离每一个正方形都将与中心正方形具有相同的颜色。每个正方形距中心最多18步，因此18个循环将确保所有正方形具有相同的颜色。它很可能以不到此的速度完成，但是只要所有正方形都是相同的颜色，就不需要停止程序。这样做更加有益。这个恒定的过程是每个测试用例108个步骤，总计10,800,000。

Java-2,480,714个步骤

我之前犯了一个小错误（我在循环中而不是循环中放置了一个关键句子：

import java.io.*;

public class HerjanPaintAI {

    BufferedReader r;
    String[] map = new String[19];
    char[][] colors = new char[19][19];
    boolean[][] reached = new boolean[19][19], checked = new boolean[19][19];
    int[] colorCounter = new int[6];
    String answer = "";
    int mapCount = 0, moveCount = 0;

    public HerjanPaintAI(){
        nextMap();

        while(true){

            int bestMove = nextRound();
            answer += bestMove;
            char t = Character.forDigit(bestMove, 10);
            for(int x = 0; x < 19; x++){
                for(int y = 0; y < 19; y++){
                    if(reached[x][y]){
                        colors[x][y] = t;
                    }else if(checked[x][y]){
                        if(colors[x][y] == t){
                            reached[x][y] = true;
                        }
                    }
                }
            }

            boolean gameOver = true;
            for(int x = 0; x < 19; x++){
                for(int y = 0; y < 19; y++){
                    if(!reached[x][y]){
                        gameOver = false;
                        break;
                    }
                }
            }

            for(int x = 0; x < 19; x++){
                for(int y = 0; y < 19; y++){
                    checked[x][y] = false;
                }
            }
            for(int i = 0; i < 6; i++)
                colorCounter[i] = 0;

            if(gameOver)
                nextMap();
        }
    }

    int nextRound(){
        for(int x = 0; x < 19; x++){
            for(int y = 0; y < 19; y++){
                if(reached[x][y]){//check what numbers are next to the reached numbers...
                    check(x, y);
                }
            }
        }

        int[] totalColorCount = new int[6];
        for(int x = 0; x < 19; x++){
            for(int y = 0; y < 19; y++){
                totalColorCount[Character.getNumericValue(colors[x][y])-1]++;
            }
        }

        for(int i = 0; i < 6; i++){
            if(totalColorCount[i] != 0 && totalColorCount[i] == colorCounter[i]){//all of this color can be reached
                return i+1;
            }
        }

        int index = -1, number = 0;
        for(int i = 0; i < 6; i++){
            if(colorCounter[i] > number){
                index = i;
                number = colorCounter[i];
            }
        }

        return index+1;
    }

    void check(int x, int y){
        if(x<18)
            handle(x+1, y, x, y);
        if(x>0)
            handle(x-1, y, x, y);
        if(y<18)
            handle(x, y+1, x, y);
        if(y>0)
            handle(x, y-1, x, y);
    }

    void handle(int x2, int y2, int x, int y){
        if(!reached[x2][y2] && !checked[x2][y2]){
            checked[x2][y2] = true;
            if(colors[x2][y2] == colors[x][y]){
                reached[x2][y2] = true;
                check(x2, y2);
            }else{
                colorCounter[Character.getNumericValue(colors[x2][y2])-1]++;
                checkAround(x2, y2);
            }
        }
    }

    void checkAround(int x2, int y2){
        if(x2<18)
            handleAround(x2+1, y2, x2, y2);
        if(x2>0)
            handleAround(x2-1, y2, x2, y2);
        if(y2<18)
            handleAround(x2, y2+1, x2, y2);
        if(y2>0)
            handleAround(x2, y2-1, x2, y2);
    }

    void handleAround(int x2, int y2, int x, int y){
        if(!reached[x2][y2] && !checked[x2][y2]){
            if(colors[x2][y2] == colors[x][y]){
                checked[x2][y2] = true;
                colorCounter[Character.getNumericValue(colors[x2][y2])-1]++;
                checkAround(x2, y2);
            }
        }
    }

    void nextMap(){
        moveCount += answer.length();
        System.out.println(answer);
        answer = "";

        for(int x = 0; x < 19; x++){
            for(int y = 0; y < 19; y++){
                reached[x][y] = false;
            }
        }

        reached[9][9] = true;

        try {
            if(r == null)
                r = new BufferedReader(new FileReader("floodtest"));

            for(int i = 0; i < 19; i++){
                map[i] = r.readLine();
            }
            r.readLine();//empty line

            if(map[0] == null){
                System.out.println("Maps solved: " + mapCount + " Steps: " + moveCount);
                r.close();
                System.exit(0);
            }
        } catch (Exception e) {e.printStackTrace();}

        mapCount++;

        for(int x = 0; x < 19; x++){
            colors[x] = map[x].toCharArray();
        }
    }

    public static void main(String[] a){
        new HerjanPaintAI();
    }
}

C-2,075,452

我知道我参加聚会非常晚，但是我看到了这个挑战，想参加。

#include <assert.h>
#include <math.h>
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>

uint64_t rand_state;

uint64_t rand_u64(void) {
    return (rand_state = rand_state * 6364136223846793005ULL + 1442695040888963407ULL);
}

uint64_t better_rand_u64(void) {
    uint64_t r = rand_u64();
    r ^= ((r >> 32) >> (r >> 60));
    return r + 1442695040888963407ULL;
}

uint32_t rand_u32(void) {return rand_u64() >> 32;}

float normal(float mu, float sigma) {
    uint64_t t = 0;
    for (int i = 0; i < 6; i++) {
        uint64_t r = rand_u64();
        uint32_t a = r;
        uint32_t b = r >> 32;
        t += a;
        t += b;
    }
    return ((float)t / (float)UINT32_MAX - 6) * sigma + mu;
}

typedef struct {
    uint8_t x;
    uint8_t y;
} Position;

#define ncolors 6
#define len 19
#define cells (len * len)
#define max_steps (len * (ncolors - 1))
#define center_x 9
#define center_y 9
#define center ((Position){center_x, center_y})

uint64_t zobrist_table[len][len];

void init_zobrist() {
    for (int y = 0; y < len; y++) {
        for (int x = 0; x < len; x++) {
            zobrist_table[y][x] = better_rand_u64();
        }
    }
}

typedef struct {
    uint64_t hash;
    uint8_t grid[len][len];
    bool interior[len][len];
    int boundary_size;
    Position boundary[cells];
} Grid;


void transition(Grid* grid, uint8_t color, int* surrounding_counts) {
    int i = 0;
    while (i < grid->boundary_size) {
        Position p = grid->boundary[i];
        uint8_t x = p.x;
        uint8_t y = p.y;
        bool still_boundary = false;
        for (int dx = -1; dx <= 1; dx++) {
            for (int dy = -1; dy <= 1; dy++) {
                if (!(dx == 0 || dy == 0)) {
                    continue;
                }
                int8_t x1 = x + dx;
                if (!(0 <= x1 && x1 < len)) {
                    continue;
                }
                int8_t y1 = y + dy;
                if (!(0 <= y1 && y1 < len)) {
                    continue;
                }
                if (grid->interior[y1][x1]) {
                    continue;
                }
                uint8_t color1 = grid->grid[y1][x1];
                if (color1 == color) {
                    grid->boundary[grid->boundary_size++] = (Position){x1, y1};
                    grid->interior[y1][x1] = true;
                    grid->hash ^= zobrist_table[y1][x1];
                } else {
                    surrounding_counts[color1]++;
                    still_boundary = true;
                }
            }
        }
        if (still_boundary) {
            i += 1;
        } else {
            grid->boundary[i] = grid->boundary[--grid->boundary_size]; 
        }
    }
}

void reset_grid(Grid* grid, int* surrounding_counts) {
    grid->hash = 0;
    memset(surrounding_counts, 0, ncolors * sizeof(int)); 
    memset(&grid->interior, 0, sizeof(grid->interior));
    grid->interior[center_y][center_x] = true;
    grid->boundary_size = 0;
    grid->boundary[grid->boundary_size++] = center; 
    transition(grid, grid->grid[center_y][center_x], surrounding_counts);
}

bool load_grid(FILE* fp, Grid* grid) {
    memset(grid, 0, sizeof(*grid));
    char buf[19 + 2];
    size_t row = 0;
    while ((fgets(buf, sizeof(buf), fp)) && row < 19) {
        if (strlen(buf) != 20) {
            break;
        }
        for (int i = 0; i < 19; i++) {
            if (!('1' <= buf[i] && buf[i] <= '6')) {
                return false;
            }
            grid->grid[row][i] = buf[i] - '1';
        }
        row++;
    }
    return row == 19;
}

typedef struct Node Node;

struct Node {
    uint64_t hash;
    float visit_counts[ncolors];
    float mean_cost[ncolors];
    float sse[ncolors];
};

#define iters 15000
#define pool_size 32768
#define pool_nodes (pool_size + 100)
#define pool_mask (pool_size - 1)

Node pool[pool_nodes];

void init_node(Node* node, uint64_t hash, int* surrounding_counts) {
    node->hash = hash;
    for (int i = 0; i < ncolors; i++) {
        if (surrounding_counts[i]) {
            node->visit_counts[i] = 1;
            node->mean_cost[i] = 20;
            node->sse[i] = 400;
        }
    }
}

Node* lookup_node(uint64_t hash) {
    size_t index = hash & pool_mask;
    for (int i = index;; i++) {
        uint64_t h = pool[i].hash;
        if (h == hash || !h) {
            return pool + i;
        }
    }
}

int rollout(Grid* grid, int* surrounding_counts, char* solution) {
    for (int i = 0;; i++) {
        int nonzero = 0;
        uint8_t colors[6];
        for (int i = 0; i < ncolors; i++) {
            if (surrounding_counts[i]) {
                colors[nonzero++] = i;
            }
        }
        if (!nonzero) {
            return i;
        }
        uint8_t color = colors[rand_u32() % nonzero]; 
        *(solution++) = color;
        assert(grid->boundary_size);
        memset(surrounding_counts, 0, 6 * sizeof(int));
        transition(grid, color, surrounding_counts);
    }
}

int simulate(Node* node, Grid* grid, int depth, char* solution) {
    float best_cost = INFINITY;
    uint8_t best_color = 255;
    for (int color = 0; color < ncolors; color++) {
        float n = node->visit_counts[color];
        if (node->visit_counts[color] == 0) {
            continue;
        }
        float sigma = sqrt(node->sse[color] / (n * n));
        float cost = node->mean_cost[color];
        cost = normal(cost, sigma);
        if (cost < best_cost) {
            best_color = color;
            best_cost = cost;
        }
    }
    if (best_color == 255) {
        return 0;
    }
    *solution++ = best_color;
    int score;
    int surrounding_counts[ncolors] = {0};
    transition(grid, best_color, surrounding_counts);
    Node* child = lookup_node(grid->hash);
    if (!child->hash) {
        init_node(child, grid->hash, surrounding_counts);
        score = rollout(grid, surrounding_counts, solution);
    } else {
        score = simulate(child, grid, depth + 1, solution);
    }
    score++;
    float n1 = ++node->visit_counts[best_color];
    float u0 = node->mean_cost[best_color];
    float u1 = node->mean_cost[best_color] = u0 + (score - u0) / n1;
    node->sse[best_color] += (score - u0) * (score - u1);
    return score;
}

int main(void) {
    FILE* fp;
    if (!(fp = fopen("floodtest", "r"))) {
        return 1;
    }
    Grid grid;
    init_zobrist();
    while (load_grid(fp, &grid)) {

        memset(pool, 0, sizeof(pool));
        int surrounding_counts[ncolors] = {0};

        reset_grid(&grid, surrounding_counts);
        Node root = {0};

        init_node(&root, grid.hash, surrounding_counts);

        char solution[max_steps] = {0};
        char best_solution[max_steps] = {0};

        int min_score = INT_MAX;

        uint64_t prev_hash = 0;
        uint64_t hash = 0;
        int same_count = 0;

        for (int iter = 0; iter < iters; iter++) {
            reset_grid(&grid, surrounding_counts);
            int score = simulate(&root, &grid, 1, solution);
            if (score < min_score) {
                min_score = score;
                memcpy(best_solution, solution, score);
            }
            hash = 0;
            for (int i = 0; i < score; i++) {
                hash ^= zobrist_table[i%len][(int)solution[i]];
            }
            if (hash == prev_hash) {
                same_count++;
                if (same_count >= 10) {
                    break;
                }
            } else {
                same_count = 0;
                prev_hash = hash;
            }
        }
        int i;
        for (i = 0; i < min_score; i++) {
            best_solution[i] += '1';
        }
        best_solution[i++] = '\n';
        best_solution[i++] = '\0';
        printf(best_solution);
        fflush(stdout);
    }
    return 0;
}

该算法基于带有Thompson采样的蒙特卡洛树搜索，以及用于减少搜索空间的换位表。我的机器大约需要12个小时。如果要检查结果，可以在https://dropfile.to/pvjYDMV中找到它们。

Java- 2,434,108 2,588,847个步骤

截至4/26，目前获胜（比Herjan领先〜46K）

很高兴，所以BackBackend先生不仅击败了我，而且我发现了一个漏洞，该漏洞产生了看似好的分数。现在已修复（也在验证程序中！Ack），但是很遗憾，我现在没有任何时间尝试取回桂冠。稍后将尝试。

这是基于我的其他解决方案的，但是它不是使用填充边缘最常见的颜色来绘画，而是使用将导致暴露具有许多相邻相同颜色正方形的边缘的颜色来绘画。称之为LookAheadPainter。如有必要，我稍后再打高尔夫球。

import java.io.*;
import java.util.*;

public class LookAheadPainter {

    static final boolean PRINT_FULL_OUTPUT = true;

    public static void main(String[] a) throws IOException {

        int totalSteps = 0, numSolved = 0;

        char[] board = new char[361];
        Scanner s = new Scanner(new File("floodtest"));
        long startTime = System.nanoTime();

        caseloop: while (s.hasNextLine()) {
            for (int l = 0; l < 19; l++) {
                String line = s.nextLine();
                if (line.isEmpty())
                    continue caseloop;
                System.arraycopy(line.toCharArray(), 0, board, l * 19, 19);
            }

            List<Character> colorsUsed = new ArrayList<>();

            for (;;) {

                FillResult fill = new FillResult(board, board[180], (char) 48, null);

                if (fill.nodesFilled.size() == 361)
                    break;

                int[] branchSizes = new int[7];

                for (int i = 1; i < 7; i++) {
                    List<Integer> seeds = new ArrayList<>();
                    for (Integer seed : fill.edges)
                        if (board[seed] == i + 48)
                            seeds.add(seed);

                    branchSizes[i] = new FillResult(fill.filledBoard, (char) (i + 48), (char) 48, seeds).nodesFilled.size();
                }

                int maxSize = 0;
                char bestColor = 0;

                for (int i = 1; i < 7; i++)
                    if (branchSizes[i] > maxSize) {
                        maxSize = branchSizes[i];
                        bestColor = (char) (i + 48);
                    }

                for (int i : fill.nodesFilled)
                    board[i] = bestColor;

                colorsUsed.add(bestColor);
                totalSteps++;
            }
            numSolved++;

            if (PRINT_FULL_OUTPUT) {
                if (numSolved % 1000 == 0)
                    System.out.println("Solved: " + numSolved); // So you know it's working
                String out = "";
                for (Character c : colorsUsed)
                    out += c;
                System.out.println(out);
            }

        }
        s.close();
        System.out.println("\nTotal steps to solve all cases: " + totalSteps);
        System.out.printf("\nSolved %d test cases in %.2f seconds", numSolved, (System.nanoTime() - startTime) / 1000000000.);
    }

    private static class FillResult {

        Set<Integer> nodesFilled, edges;
        char[] filledBoard;

        FillResult(char[] board, char target, char replacement, List<Integer> seeds) {
            Stack<Integer> nodes = new Stack<>();
            nodesFilled = new HashSet<>();
            edges = new HashSet<>();

            if (seeds == null)
                nodes.push(180);
            else
                for (int i : seeds)
                    nodes.push(i);

            filledBoard = new char[361];
            System.arraycopy(board, 0, filledBoard, 0, 361);

            while (!nodes.empty()) {
                int n = nodes.pop();
                if (n < 0 || n > 360)
                    continue;
                if (filledBoard[n] == target) {
                    filledBoard[n] = replacement;
                    nodesFilled.add(n);
                    if (n % 19 > 0)
                        nodes.push(n - 1);
                    if (n % 19 < 18)
                        nodes.push(n + 1);
                    if (n / 19 > 0)
                        nodes.push(n - 19);
                    if (n / 19 < 18)
                        nodes.push(n + 19);
                } else
                    edges.add(n);
            }
        }
    }
}

编辑：我编写了一个验证程序，可以随时使用，它需要一个step.txt文件，其中包含程序输出的步骤以及Floodlight文件：编辑-编辑：（请参阅OP）

如果有人发现问题，请报告给我！

C-2,480,714个步骤

仍然不是最佳选择，但是它现在更快并且得分更高。

#include <stdio.h>
#include <string.h>
#include <stdbool.h>

char map[19][19], reach[19][19];
int reachsum[6], totalsum[6];

bool loadmap(FILE *fp)
{
    char buf[19 + 2];
    size_t row = 0;

    while (fgets(buf, sizeof buf, fp) && row < 19) {
        if (strlen(buf) != 20)
            break;
        memcpy(map[row++], buf, 19);
    }
    return row == 19;
}

void calcreach(bool first, size_t row, size_t col);
void check(char c, bool first, size_t row, size_t col)
{
    if (map[row][col] == c)
        calcreach(first, row, col);
    else if (first)
        calcreach(false, row, col);
}

void calcreach(bool first, size_t row, size_t col)
{
    char c = map[row][col];

    reach[row][col] = c;
    reachsum[c - '1']++;
    if (row < 18 && !reach[row + 1][col])
        check(c, first, row + 1, col);
    if (col < 18 && !reach[row][col + 1])
        check(c, first, row, col + 1);
    if (row > 0 && !reach[row - 1][col])
        check(c, first, row - 1, col);
    if (col > 0 && !reach[row][col - 1])
        check(c, first, row, col - 1);
}

void calctotal()
{
    size_t row, col;

    for (row = 0; row < 19; row++)
        for (col = 0; col < 19; col++)
            totalsum[map[row][col] - '1']++;
}

void apply(char c)
{
    char d = map[9][9];
    size_t row, col;

    for (row = 0; row < 19; row++)
        for (col = 0; col < 19; col++)
            if (reach[row][col] == d)
                map[row][col] = c;
}

int main()
{
    char c, best;
    size_t steps = 0;
    FILE *fp;

    if (!(fp = fopen("floodtest", "r")))
        return 1;

    while (loadmap(fp)) {
        do {
            memset(reach, 0, sizeof reach);
            memset(reachsum, 0, sizeof reachsum);
            calcreach(true, 9, 9);
            if (reachsum[map[9][9] - '1'] == 361)
                break;

            memset(totalsum, 0, sizeof totalsum);
            calctotal();

            reachsum[map[9][9] - '1'] = 0;
            for (best = 0, c = 0; c < 6; c++) {
                if (!reachsum[c])
                    continue;
                if (reachsum[c] == totalsum[c]) {
                    best = c;
                    break;
                } else if (reachsum[c] > reachsum[best]) {
                    best = c;
                }
            }

            apply(best + '1');
        } while (++steps);
    }

    fclose(fp);

    printf("steps: %zu\n", steps);
    return 0;
}

Java- 2,245,529 2,201,995个步骤

在深度5进行并行和缓存树搜索，最大程度地减少了“孤岛”的数量。由于从第4层到第5层的改进很小，因此我认为没有更多改进的意义。但是如果需要改进，我的直觉是说要计算岛屿的数量作为两个州之间的差异，而不是重新计算所有内容。

当前输出到stdout，直到我知道验证者的输入格式。

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class FloodPaint {

    private static final ForkJoinPool FORK_JOIN_POOL = new ForkJoinPool();

    public static void main(String[] arg) throws IOException, InterruptedException, ExecutionException {
        try (BufferedReader reader = new BufferedReader(new FileReader("floodtest"))) {
            int sum = 0;
            State initState = readNextInitState(reader);
            while (initState != null) {
                List<Integer> solution = generateSolution(initState);
                System.out.println(solution);
                sum += solution.size();
                initState = readNextInitState(reader);
            }
            System.out.println(sum);
        }
    }

    private static State readNextInitState(BufferedReader reader) throws IOException {
        int[] initGrid = new int[State.DIM * State.DIM];
        String line = reader.readLine();
        while ((line != null) && line.isEmpty()) {
            line = reader.readLine();
        }
        if (line == null) {
            return null;
        }
        for (int rowNo = 0; rowNo < State.DIM; ++rowNo) {
            for (int colNo = 0; colNo < State.DIM; ++colNo) {
                initGrid[(State.DIM * rowNo) + colNo] = line.charAt(colNo) - '0';
            }
            line = reader.readLine();
        }
        return new State(initGrid);
    }

    private static List<Integer> generateSolution(State initState) throws InterruptedException, ExecutionException {
        List<Integer> solution = new LinkedList<>();
        StateFactory stateFactory = new StateFactory();
        State state = initState;
        while (!state.isSolved()) {
            int num = findGoodNum(state, stateFactory);
            solution.add(num);
            state = state.getNextState(num, stateFactory);
        }
        return solution;
    }

    private static int findGoodNum(State state, StateFactory stateFactory) throws InterruptedException, ExecutionException {
        SolverTask task = new SolverTask(state, stateFactory);
        FORK_JOIN_POOL.invoke(task);
        return task.get();
    }

}

class SolverTask extends RecursiveTask<Integer> {

    private static final int DEPTH = 5;

    private final State state;
    private final StateFactory stateFactory;

    SolverTask(State state, StateFactory stateFactory) {
        this.state = state;
        this.stateFactory = stateFactory;
    }

    @Override
    protected Integer compute() {
        try {
            Map<Integer,AnalyzerTask> tasks = new HashMap<>();
            for (int num = 1; num <= 6; ++num) {
                if (num != state.getCenterNum()) {
                    State nextState = state.getNextState(num, stateFactory);
                    AnalyzerTask task = new AnalyzerTask(nextState, DEPTH - 1, stateFactory);
                    tasks.put(num, task);
                }
            }
            invokeAll(tasks.values());
            int bestValue = Integer.MAX_VALUE;
            int bestNum = -1;
            for (Map.Entry<Integer,AnalyzerTask> taskEntry : tasks.entrySet()) {
                int value = taskEntry.getValue().get();
                if (value < bestValue) {
                    bestValue = value;
                    bestNum = taskEntry.getKey();
                }
            }
            return bestNum;
        } catch (InterruptedException | ExecutionException ex) {
            throw new RuntimeException(ex);
        }
    }

}

class AnalyzerTask extends RecursiveTask<Integer> {

    private static final int DEPTH_THRESHOLD = 3;

    private final State state;
    private final int depth;
    private final StateFactory stateFactory;

    AnalyzerTask(State state, int depth, StateFactory stateFactory) {
        this.state = state;
        this.depth = depth;
        this.stateFactory = stateFactory;
    }

    @Override
    protected Integer compute() {
        return (depth < DEPTH_THRESHOLD) ? analyze() : split();
    }

    private int analyze() {
        return analyze(state, depth);
    }

    private int analyze(State state, int depth) {
        if (state.isSolved()) {
            return -depth;
        }
        if (depth == 0) {
            return state.getNumIslands();
        }
        int bestValue = Integer.MAX_VALUE;
        for (int num = 1; num <= 6; ++num) {
            if (num != state.getCenterNum()) {
                State nextState = state.getNextState(num, stateFactory);
                int nextValue = analyze(nextState, depth - 1);
                bestValue = Math.min(bestValue, nextValue);
            }
        }
        return bestValue;
    }

    private int split() {
        try {
            if (state.isSolved()) {
                return -depth;
            }
            Collection<AnalyzerTask> tasks = new ArrayList<>(5);
            for (int num = 1; num <= 6; ++num) {
                State nextState = state.getNextState(num, stateFactory);
                AnalyzerTask task = new AnalyzerTask(nextState, depth - 1, stateFactory);
                tasks.add(task);
            }
            invokeAll(tasks);
            int bestValue = Integer.MAX_VALUE;
            for (AnalyzerTask task : tasks) {
                int nextValue = task.get();
                bestValue = Math.min(bestValue, nextValue);
            }
            return bestValue;
        } catch (InterruptedException | ExecutionException ex) {
            throw new RuntimeException(ex);
        }
    }

}

class StateFactory {

    private static final int INIT_CAPACITY = 40000;
    private static final float LOAD_FACTOR = 0.9f;

    private final ReadWriteLock cacheLock = new ReentrantReadWriteLock();
    private final Map<List<Integer>,State> cache = new HashMap<>(INIT_CAPACITY, LOAD_FACTOR);

    State get(int[] grid) {
        List<Integer> stateKey = new IntList(grid);
        State state;
        cacheLock.readLock().lock();
        try {
            state = cache.get(stateKey);
        } finally {
            cacheLock.readLock().unlock();
        }
        if (state == null) {
            cacheLock.writeLock().lock();
            try {
                state = cache.get(stateKey);
                if (state == null) {
                    state = new State(grid);
                    cache.put(stateKey, state);
                }
            } finally {
                cacheLock.writeLock().unlock();
            }
        }
        return state;
    }

}

class State {

    static final int DIM = 19;
    private static final int CENTER_INDEX = ((DIM * DIM) - 1) / 2;

    private final int[] grid;
    private int numIslands;

    State(int[] grid) {
        this.grid = grid;
        numIslands = calcNumIslands(grid);
    }

    private static int calcNumIslands(int[] grid) {
        int numIslands = 0;
        BitSet uncounted = new BitSet(DIM * DIM);
        uncounted.set(0, DIM * DIM);
        int index = -1;
        while (!uncounted.isEmpty()) {
            index = uncounted.nextSetBit(index + 1);
            BitSet island = new BitSet(DIM * DIM);
            generateIsland(grid, index, grid[index], island);
            ++numIslands;
            uncounted.andNot(island);
        }
        return numIslands;
    }

    private static void generateIsland(int[] grid, int index, int num, BitSet island) {
        if ((grid[index] == num) && !island.get(index)) {
            island.set(index);
            if ((index % DIM) > 0) {
                generateIsland(grid, index - 1, num, island);
            }
            if ((index % DIM) < (DIM - 1)) {
                generateIsland(grid, index + 1, num, island);
            }
            if ((index / DIM) > 0) {
                generateIsland(grid, index - DIM, num, island);
            }
            if ((index / DIM) < (DIM - 1)) {
                generateIsland(grid, index + DIM, num, island);
            }
        }
    }

    int getCenterNum() {
        return grid[CENTER_INDEX];
    }

    boolean isSolved() {
        return numIslands == 1;
    }

    int getNumIslands() {
        return numIslands;
    }

    State getNextState(int num, StateFactory stateFactory) {
        int[] nextGrid = grid.clone();
        if (num != getCenterNum()) {
            flood(nextGrid, CENTER_INDEX, getCenterNum(), num);
        }
        State nextState = stateFactory.get(nextGrid);
        return nextState;
    }

    private static void flood(int[] grid, int index, int fromNum, int toNum) {
        if (grid[index] == fromNum) {
            grid[index] = toNum;
            if ((index % 19) > 0) {
                flood(grid, index - 1, fromNum, toNum);
            }
            if ((index % 19) < (DIM - 1)) {
                flood(grid, index + 1, fromNum, toNum);
            }
            if ((index / 19) > 0) {
                flood(grid, index - DIM, fromNum, toNum);
            }
            if ((index / 19) < (DIM - 1)) {
                flood(grid, index + DIM, fromNum, toNum);
            }
        }
    }

}

class IntList extends AbstractList<Integer> implements List<Integer> {

    private final int[] arr;
    private int hashCode = -1;

    IntList(int[] arr) {
        this.arr = arr;
    }

    @Override
    public int size() {
        return arr.length;
    }

    @Override
    public Integer get(int index) {
        return arr[index];
    }

    @Override
    public Integer set(int index, Integer value) {
        int oldValue = arr[index];
        arr[index] = value;
        return oldValue;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof IntList) {
            IntList arg = (IntList) obj;
            return Arrays.equals(arr, arg.arr);
        }
        return super.equals(obj);
    }

    @Override
    public int hashCode() {
        if (hashCode == -1) {
            hashCode = 1;
            for (int elem : arr) {
                hashCode = 31 * hashCode + elem;
            }
        }
        return hashCode;
    }

}

我的上次输入：C-2,384,020步

这次是“检查所有可能性”的一项...将该深度设置为3可获得此分数。深度为5时应给出〜2.1M步...太慢了。深度20+给出的步数最少（它只检查所有比赛和最短的路线获胜）...步数最少，尽管我讨厌它，因为它只好一点点，但是性能很差。我更喜欢我的其他C条目，该条目也在本文中。

#include <stdio.h>
#include <string.h>
#include <stdbool.h>

char map[19][19], reach[19][19];
int reachsum[6], totalsum[6], mapCount = 0;
FILE *stepfile;

bool loadmap(FILE *fp)
{
    fprintf(stepfile, "%s", "\n");

    mapCount++;

    char buf[19 + 2];
    size_t row = 0;

    while (fgets(buf, sizeof buf, fp) && row < 19) {
        if (strlen(buf) != 20)
            break;
        memcpy(map[row++], buf, 19);
    }
    return row == 19;
}

void calcreach(bool first, size_t row, size_t col);
void check(char c, bool first, size_t row, size_t col)
{
    if (map[row][col] == c)
        calcreach(first, row, col);
    else if (first)
        calcreach(false, row, col);
}

void calcreach(bool first, size_t row, size_t col)
{
    char c = map[row][col];

    reach[row][col] = c;
    reachsum[c - '1']++;
    if (row < 18 && !reach[row + 1][col])
        check(c, first, row + 1, col);
    if (col < 18 && !reach[row][col + 1])
        check(c, first, row, col + 1);
    if (row > 0 && !reach[row - 1][col])
        check(c, first, row - 1, col);
    if (col > 0 && !reach[row][col - 1])
        check(c, first, row, col - 1);
}

void calctotal()
{
    size_t row, col;

    for (row = 0; row < 19; row++)
        for (col = 0; col < 19; col++)
            totalsum[map[row][col] - '1']++;
}

void apply(char c)
{
    char d = map[9][9];
    size_t row, col;

    for (row = 0; row < 19; row++)
        for (col = 0; col < 19; col++)
            if (reach[row][col] == d)
                map[row][col] = c;
}

int pown(int x, int y){
    int p = 1;
    for(int i = 0; i < y; i++){
        p = p * x;
    }

    return p;
}

int main()
{
    size_t steps = 0;
    FILE *fp;

    if (!(fp = fopen("floodtest", "r")))
        return 1;
    if(!(stepfile = fopen("steps.txt", "w")))
        return 1;

    const int depth = 5;
    char possibilities[pown(6, depth)][depth];
    int t = 0;
    for(int a = 0; a < 6; a++){
        for(int b = 0; b < 6; b++){
            for(int c = 0; c < 6; c++){
                for(int d = 0; d < 6; d++){
                    for(int e = 0; e < 6; e++){
                        possibilities[t][0] = (char)(a + '1');
                        possibilities[t][1] = (char)(b + '1');
                        possibilities[t][2] = (char)(c + '1');
                        possibilities[t][3] = (char)(d + '1');
                        possibilities[t++][4] = (char)(e + '1');
                    }
                }
            }
        }
    }
    poes:
    while (loadmap(fp)) {
        do {
            char map2[19][19];
            memcpy(map2, map, sizeof(map));

            memset(reach, 0, sizeof reach);
            memset(reachsum, 0, sizeof reachsum);
            calcreach(true, 9, 9);

            int best = 0, index = 0, end = depth;
            for(int i = 0; i < pown(6, depth); i++){
                for(int d = 0; d < end; d++){

                    apply(possibilities[i][d]);

                    memset(reach, 0, sizeof reach);
                    memset(reachsum, 0, sizeof reachsum);
                    calcreach(true, 9, 9);

                    if(reachsum[map[9][9] - '1'] == 361 && d < end){
                        end = d+1;
                        index = i;
                        break;
                    }
                }
                if(end == depth && best < reachsum[map[9][9] - '1']){
                    best = reachsum[map[9][9] - '1'];
                    index = i;
                }

                memcpy(map, map2, sizeof(map2));
                memset(reach, 0, sizeof reach);
                memset(reachsum, 0, sizeof reachsum);
                calcreach(true, 9, 9);
            }

            for(int d = 0; d < end; d++){

                apply(possibilities[index][d]);

                memset(reach, 0, sizeof reach);
                memset(reachsum, 0, sizeof reachsum);
                calcreach(true, 9, 9);

                fprintf(stepfile, "%c", possibilities[index][d]);
                steps++;
            }
            if(reachsum[map[9][9] - '1'] == 361)
                goto poes;
        } while (1);
    }

    fclose(fp);
    fclose(stepfile);

    printf("steps: %zu\n", steps);
    return 0;
}

用C语言编写的另一种改进的AI-2,445,761步

基于SteelTermite的：

#include <stdio.h>
#include <string.h>
#include <stdbool.h>

char map[19][19], reach[19][19];
int reachsum[6], totalsum[6], mapCount = 0;
FILE *stepfile;

bool loadmap(FILE *fp)
{
    fprintf(stepfile, "%s", "\n");

    if(mapCount % 1000 == 0)
        printf("mapCount = %d\n", mapCount);

    mapCount++;

    char buf[19 + 2];
    size_t row = 0;

    while (fgets(buf, sizeof buf, fp) && row < 19) {
        if (strlen(buf) != 20)
            break;
        memcpy(map[row++], buf, 19);
    }
    return row == 19;
}

void calcreach(bool first, size_t row, size_t col);
void check(char c, bool first, size_t row, size_t col)
{
    if (map[row][col] == c)
        calcreach(first, row, col);
    else if (first)
        calcreach(false, row, col);
}

void calcreach(bool first, size_t row, size_t col)
{
    char c = map[row][col];

    reach[row][col] = c;
    reachsum[c - '1']++;
    if (row < 18 && !reach[row + 1][col])
        check(c, first, row + 1, col);
    if (col < 18 && !reach[row][col + 1])
        check(c, first, row, col + 1);
    if (row > 0 && !reach[row - 1][col])
        check(c, first, row - 1, col);
    if (col > 0 && !reach[row][col - 1])
        check(c, first, row, col - 1);
}

void calctotal()
{
    size_t row, col;

    for (row = 0; row < 19; row++)
        for (col = 0; col < 19; col++)
            totalsum[map[row][col] - '1']++;
}

void apply(char c)
{
    char d = map[9][9];
    size_t row, col;

    for (row = 0; row < 19; row++)
        for (col = 0; col < 19; col++)
            if (reach[row][col] == d)
                map[row][col] = c;
}

int main()
{
    char c, best, answer;
    size_t steps = 0;
    FILE *fp;

    if (!(fp = fopen("floodtest", "r")))
        return 1;
    if(!(stepfile = fopen("steps.txt", "w")))
            return 1;

    while (loadmap(fp)) {
        do {
            memset(reach, 0, sizeof reach);
            memset(reachsum, 0, sizeof reachsum);
            calcreach(true, 9, 9);
            if (reachsum[map[9][9] - '1'] == 361)
                break;

            memset(totalsum, 0, sizeof totalsum);
            calctotal();

            reachsum[map[9][9] - '1'] = 0;
            for (best = 0, c = 0; c < 6; c++) {
                if (!reachsum[c])
                    continue;
                if (reachsum[c] == totalsum[c]) {
                    best = c;
                    goto outLoop;
                } else if (reachsum[c] > reachsum[best]) {
                    best = c;
                }
            }

            char map2[19][19];
            memcpy(map2, map, sizeof(map));

            int temp = best;
            for(c = 0; c < 6; c++){

                if(c != best){

                    apply(c + '1');

                    memset(reach, 0, sizeof reach);
                    memset(reachsum, 0, sizeof reachsum);
                    calcreach(true, 9, 9);
                    if (reachsum[best] == totalsum[best]) {

                        memcpy(map, map2, sizeof(map2));
                        memset(reach, 0, sizeof reach);
                        memset(reachsum, 0, sizeof reachsum);
                        calcreach(true, 9, 9);

                        if(temp == -1)
                            temp = c;
                        else if(reachsum[c] > reachsum[temp])
                            temp = c;
                    }

                    memcpy(map, map2, sizeof(map2));
                    memset(reach, 0, sizeof reach);
                    memset(reachsum, 0, sizeof reachsum);
                    calcreach(true, 9, 9);
                }
            }

outLoop:    answer = (char)(temp + '1');
            fprintf(stepfile, "%c", answer);
            apply(answer);
        } while (++steps);
    }

    fclose(fp);
    fclose(stepfile);

    printf("steps: %zu\n", steps);
    return 0;
}

Java- 2,610,797 4,780,841个步骤

（Fill-Bug修复了，分数现在明显变差了-_-）

这是我的基本参考算法提交内容，只是对绘制区域边缘上的正方形进行直方图绘制，并使用最常见的颜色进行绘制。在几分钟内运行100k。

显然不会赢，但是肯定不会持续。我可能会再提交一些关于智能的东西。随意使用此算法作为起点。

取消注释注释行中的完整输出。默认为打印已执行的步骤数。

import java.io.*;
import java.util.*;

public class PainterAI {

    public static void main(String[] args) throws IOException {

        int totalSteps = 0, numSolved = 0;

        char[] board = new char[361];
        Scanner s = new Scanner(new File("floodtest"));
        long startTime = System.nanoTime();
        caseloop: while (s.hasNextLine()) {
            for (int l = 0; l < 19; l++) {
                String line = s.nextLine();
                if (line.isEmpty())
                    continue caseloop;
                System.arraycopy(line.toCharArray(), 0, board, l * 19, 19);
            }

            List<Character> colorsUsed = new ArrayList<>();
            Stack<Integer> nodes = new Stack<>();

            for (;; totalSteps++) {
                char p = board[180];
                int[] occurrences = new int[7];
                nodes.add(180);
                int numToPaint = 0;
                while (!nodes.empty()) {
                    int n = nodes.pop();
                    if (n < 0 || n > 360)
                        continue;
                    if (board[n] == p) {
                        board[n] = 48;
                        numToPaint++;
                        if (n % 19 > 0)
                            nodes.push(n - 1);
                        if(n%19<18)
                            nodes.push(n + 1);
                        if(n/19>0)
                            nodes.push(n - 19);
                        if(n/19<18)
                            nodes.push(n + 19);
                    } else
                        occurrences[board[n] - 48]++;
                }
                if (numToPaint == 361)
                    break;
                char mostFrequent = 0;
                int times = -1;
                for (int i = 1; i < 7; i++)
                    if (occurrences[i] > times) {
                        times = occurrences[i];
                        mostFrequent = (char) (i + 48);
                    }
                for (int i = 0; i < 361; i++)
                    if (board[i] == 48)
                        board[i] = mostFrequent;
                //colorsUsed.add(mostFrequent);
            }
            numSolved++;

            /*String out = "";
            for (Character c : colorsUsed)
                out += c;
            System.out.println(out); //print output*/
        }
        s.close();
        System.out.println("Total steps to solve all cases: " + totalSteps);
        System.out.printf("\nSolved %d test cases in %.2f seconds", numSolved, (System.nanoTime() - startTime) / 1000000000.);
    }
}

可以达到860个字符（不包括格式化换行符），但是如果我想尝试的话，可以缩水更多：

import java.io.*;import java.util.*;class P{
public static void main(String[]a)throws Exception{int t=0;char[]b=new char[361];
Scanner s=new Scanner(new File("floodtest"));c:while(s.hasNextLine()){
for(int l=0;l<19;l++){String L=s.nextLine();if(L.isEmpty())continue c;
System.arraycopy(L.toCharArray(),0,b,l*19,19);}List<Character>u=new ArrayList<>();
Stack<Integer>q=new Stack<>();for(int[]o=new int[7];;t++){char p=b[180];q.add(180);
int m=0;while(!q.empty()){int n=q.pop();if(n<0|n>360)continue;if(b[n]==p){b[n]=48;m++;
if(n%19>0)q.add(n-1);if(n%19<18)q.add(n+1);if(n/19>0)q.add(n-19);if(n/19<18)
q.add(n+19);}else o[b[n]-48]++;}if(m==361)break;
char f=0;int h=0;for(int i=1;i<7;i++)if(o[i]>h){h=o[i];f=(char)(i+48);}
for(int i=0;i<361;i++)if(b[i]==48)b[i]=f;u.add(f);}String y="";for(char c:u)y+=c;
System.out.println(y);}s.close();System.out.println("Steps: "+t);}}

Haskell-2,475,056步

算法类似于MrBackend在评论中建议的算法。区别在于：他的建议找到了通往成本最高的平方的最便宜的路径，而我的贪婪地降低了每一步的图形偏心率。

import Data.Array
import qualified Data.Map as M
import Data.Word
import Data.List
import Data.Maybe
import Data.Function (on)
import Data.Monoid
import Control.Arrow
import Control.Monad (liftM)
import System.IO
import System.Environment
import Control.Parallel.Strategies
import Control.DeepSeq

type Grid v = Array (Word8,Word8) v

main = do
  (ifn:_) <- getArgs
  hr <- openFile ifn ReadMode
  sp <- liftM parseFile $ hGetContents hr
  let (len,sol) = turns (map solve sp `using` parBuffer 3 (evalList rseq))
  putStrLn $ intercalate "\n" $ map (concatMap show) sol
  putStrLn $ "\n\nTotal turns: " ++ (show len)

turns :: [[a]] -> (Integer,[[a]])
turns l = rl' 0 l where
  rl' c [] = (c,[])
  rl' c (k:r) = let
   s = c + genericLength k
   (s',l') = s `seq` rl' s r
   in (s',k:l')

centrepoint :: Grid v -> (Word8,Word8)
centrepoint g = let
  ((x0,y0),(x1,y1)) = bounds g
  med l h = let t = l + h in t `div` 2 + t `mod` 2
  in (med x0 x1, med y0 y1)

neighbours :: Grid v -> (Word8,Word8) -> [(Word8,Word8)]
neighbours g (x,y) = filter
  (inRange $ bounds g)
  [(x,y+1),(x+1,y),(x,y-1),(x-1,y)]

areas :: Eq v => Grid v -> [[(Word8,Word8)]]
areas g = p $ indices g where
  p [] = []
  p (a:r) = f : p (r \\ f) where
    f = s g [a] []
s g [] _ = []
s g (h:o) v = let
  n = filter (((==) `on` (g !)) h) $ neighbours g h
  in h : s g ((n \\ (o ++ v)) ++ o) (h : v)

applyFill :: Eq v => v -> Grid v -> Grid v
applyFill c g = g // (zip fa $ repeat c) where
  fa = s g [centrepoint g] []

solve g = solve' gr' where
  aa = areas g
  cp = centrepoint g
  ca = head $ head $ filter (elem cp) aa
  gr' = M.fromList $ map (
    \r1 -> (head r1, map head $ filter (
      \r2 -> head r1 /= head r2 &&
        (not $ null $ intersect (concatMap (neighbours g) r1) r2)
     ) aa
    )
   ) aa
  solve' gr
    | null $ tail $ M.keys $ gr = []
    | otherwise = best : solve' ngr where
      djk _ [] = []
      djk v ((n,q):o) = (n,q) : djk (q:v) (
        o ++ zip (repeat (n+1))
        ((gr M.! q) \\ (v ++ map snd o))
       )
      dout = djk [] [(0,ca)]
      din = let
        m = maximum $ map fst dout
        s = filter ((== m) . fst) dout
        in djk [] s
      rc = filter (flip elem (gr M.! ca) . snd) din
      frc = let
        m = minimum $ map fst rc
        in map snd $ filter ((==m) . fst) rc
      msq = concat $ filter (flip elem frc . head) aa
      clr = map (length &&& head) $ group $ sort $ map (g !) msq
      best = snd $ maximumBy (compare `on` fst) clr
      ngr = let
        ssm = filter ((== best) . (g !)) $ map snd rc
        sml = (concatMap (gr M.!) ssm)
        ncl = ((gr M.! ca) ++ sml) \\ (ca : ssm)
        brk = M.insert ca ncl $ M.filterWithKey (\k _ ->
          (not . flip elem ssm) k
         ) gr
        in M.map 
          (\l -> nub $ map (\e -> if e `elem` ssm then ca else e) l)
          brk


parseFile :: String -> [Grid Word8]
parseFile f = map mk $ filter (not . null . head) $ groupBy ((==) `on` null) $
  map (map ((read :: String -> Word8) . (:[]))) $ lines f where
    mk :: [[Word8]] -> Grid Word8
    mk m = let
      w = fromIntegral (length $ head m) - 1
      h = fromIntegral (length m) - 1
      in array ((0,0),(w,h)) [ ((x,y),v) |
        (y,l) <- zip [h,h-1..] m,
        (x,v) <- zip [0..] l
       ]

showGrid :: Grid Word8 -> String
showGrid g = intercalate "\n" l where
  l = map sl $ groupBy ((==) `on` snd) $
    sortBy ((flip (compare `on` snd)) <> (compare `on` fst)) $
    indices g
  sl = intercalate " " . map (show . (g !))

testsolve = do
  hr <- openFile "floodtest" ReadMode
  sp <- liftM (head . parseFile) $ hGetContents hr
  let
   sol = solve sp
   a = snd $ mapAccumL (\g s -> let g' = applyFill s g in (g',g')) sp sol
  sequence_ $ map (\g -> putStrLn (showGrid g) >> putStrLn "\n") a

C＃-2,383,569

这是对可能的解决方案的深入遍历，大致选择了最佳的改进路径（与Herjan的C条目相似/相同），只是在看到Herjan发布相同的数字后我巧妙地颠倒了候选解决方案的生成顺序。不过需要12个小时以上才能运行。

class Solver
{
    static void Main()
    {
        int depth = 3;
        string text = File.ReadAllText(@"C:\TEMP\floodtest.txt");
        text = text.Replace("\n\n", ".").Replace("\n", "");
        int count = 0;
        string[] tests = text.Split(new char[] { '.' }, StringSplitOptions.RemoveEmptyEntries);
        for (int i = 0; i < tests.Length; i++)
        {
            Solver s = new Solver(tests[i]);
            string k1 = s.solve(depth);
            count += k1.Length;
            Console.WriteLine(((100 * i) / tests.Length) + " " + i + " " + k1.Length + " " + count + " " + k1);
        }
        Console.WriteLine(count);
    }

    public readonly int MAX_DIM;
    public char[] board;
    public Solver(string prob)
    {
        board = read(prob);
        MAX_DIM = (int)Math.Sqrt(board.Length);
    }

    public string solve(int d)
    {
        var sol = "";
        while (score(eval(copy(board), sol)) != board.Length)
        {
            char[] b = copy(board);
            eval(b, sol);

            var canidates = new List<string>();
            buildCanidates("", canidates, d);
            var best = canidates.Select(c => new {score = score(eval(copy(b), c)), sol = c}).ToList().OrderByDescending(t=>t.score).ThenBy(v => v.sol.Length).First();
            sol = sol + best.sol[0];
        }
        return sol;
    }

    public void buildCanidates(string b, List<string> r, int d)
    {
        if(b.Length>0)
            r.Add(b);
        if (d > 0)
        {
            r.Add(b);
            for (char i = '6'; i >= '1'; i--)
                if(b.Length == 0 || b[b.Length-1] != i)
                    buildCanidates(b + i, r, d - 1);
        }
    }

    public char[] read(string s)
    {
        return s.Where(c => c >= '0' && c <= '9').ToArray();
    }

    public void print(char[] b)
    {
        for (int i = 0; i < MAX_DIM; i++)
        {
            for(int j=0; j<MAX_DIM; j++)
                Console.Write(b[i*MAX_DIM+j]);
            Console.WriteLine();
        }
        Console.WriteLine();
    }

    public char[] copy(char[] b)
    {
        char[] n = new char[b.Length];
        for (int i = 0; i < b.Length; i++)
            n[i] = b[i];
        return n;
    }

    public char[] eval(char[] b, string sol)
    {
        foreach (char c in sol)
            eval(b, c);
        return b;
    }

    public void eval(char[] b, char c)
    {
        foreach (var l in flood(b))
            b[l] = c;
    }

    public int score(char[] b)
    {
        return flood(b).Count;
    }

    public List<int> flood(char[] b)
    {
        int start = (MAX_DIM * (MAX_DIM / 2)) + (MAX_DIM / 2);
        var check = new List<int>(MAX_DIM * MAX_DIM);
        bool[] seen = new bool[b.Length];
        var hits = new List<int>(MAX_DIM*MAX_DIM);

        check.Add(start);
        seen[start]=true;
        char target = b[start];

        int at = 0;
        while (at<check.Count)
        {
            int toCheck = check[at++];
            if (b[toCheck] == target)
            {
                addNeighbors(check, seen, toCheck);
                hits.Add(toCheck);
            }
        }
        return hits;
    }

    public void addNeighbors(List<int> check, bool[] seen, int loc)
    {
        int x = loc / MAX_DIM;
        int y = loc % MAX_DIM;
        addNeighbor(check, seen, x, y - 1);
        addNeighbor(check, seen, x, y + 1);
        addNeighbor(check, seen, x - 1, y);
        addNeighbor(check, seen, x + 1, y);
    }

    public void addNeighbor(List<int> check, bool[] seen, int x, int y)
    {
        if (x >= 0 && x < MAX_DIM && y >= 0 && y < MAX_DIM)
        {
            int l = (x * MAX_DIM) + y;
            if (!seen[l])
            {
                seen[l] = true;
                check.Add(l);
            }
        }
    }
}

爪哇-2,403,189

BUILD SUCCESSFUL (total time: 220 minutes 15 seconds)

这应该是我对蛮力的尝试。但！我对单一深度“最佳”选择的第一个实现产生了：

2,589,328 - BUILD SUCCESSFUL (total time: 3 minutes 11 seconds)

两者使用的代码都是相同的，蛮力存储了其他可能动作的“快照”，并在所有可能动作上运行算法。

• 问题

如果使用“多次”通过方法运行，则会发生随机故障。我在单元测试中设置了前100个拼图条目，可以通过100％，但不能达到100％的时间。为了弥补这一点，我只是在失败时跟踪了当前的难题编号，并在上一个中断的地方开始了新的线程拾取。每个线程将其各自的结果写入文件。然后将文件池压缩为单个文件。

• 方法

Node代表木板的方块/正方形，并存储对所有邻居的引用。可跟踪三个Set<Node>变量：Remaining，Painted，Targets。每次迭代Targets都会candidate根据值对所有节点进行分组，然后选择target value根据“受影响”节点的数量。然后，这些受影响的节点将成为下一个迭代的目标。

源代码分布在许多类中，并且摘要与整个上下文的意义不大。我的源代码可以通过GitHub浏览。我还弄乱了JSFiddle演示以进行可视化。

不过，我的主力方法来自Solver.java：

public void flood() {

 final Data data = new Data();
 consolidateCandidates(data, targets);

 input.add(data.getTarget());

 if(input.size() > SolutionRepository.getInstance().getThreshold()){
  //System.out.println("Exceeded threshold: " + input.toString());
  cancelled = true;
 }
 paintable.addAll(data.targets());
 remaining.removeAll(data.targets());

 if(!data.targets().isEmpty()){
  targets = data.potentialTargets(data.targets(), paintable);

  data.setPaintable(paintable);
  data.setRemaining(remaining);
  data.setInput(input);

  SolutionRepository.getInstance().addSnapshot(data, input);
 }
}

C＃-2,196,462 2,155,834

实际上，这与我的其他求解器相同，是“寻找最佳后代”方法，但是经过一些优化，仅凭并行性，它几乎可以在不到10小时的时间内达到深度5。在测试过程中，我还发现了一个原始错误，因此该算法偶尔会采用无效的路线到达最终状态（这并没有考虑得分= 64的状态深度；在研究深度结果时发现了该错误） = 7）。

该解决方案与以前的求解器之间的主要区别在于，它会将Flood Game状态保留在内存中，因此不必重新生成6 ^ 5状态。根据运行期间的CPU使用情况，我可以确定这已经从CPU限制转移到了内存带宽限制。非常有趣。如此多的罪过。

编辑：由于种种原因，深度5算法并非总能产生最佳结果。为了提高性能，让我们只做深度5 ...和4 ...以及3和2和1，然后看看哪个是最好的。确实刮掉了另外40k个动作。由于深度5是大部分时间，因此将4乘以1只会将运行时间从〜10小时增加到〜11小时。好极了！

using System;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Collections.Generic;

public class Program
{
    static void Main()
    {
        int depth = 5;
        string text = File.ReadAllText(@"C:\TEMP\floodtest.txt");
        text = text.Replace("\n\n", ".").Replace("\n", "");
        int count = 0;
        string[] tests = text.Split(new [] { '.' }, StringSplitOptions.RemoveEmptyEntries);

        Stopwatch start = Stopwatch.StartNew();

        const int parChunk = 16*16;
        for (int i = 0; i < tests.Length; i += parChunk)
        {
            //did not know that parallel select didn't respect order
            string[] sols = tests.Skip(i).Take(parChunk).AsParallel().Select((t, idx) => new { s = new Solver2(t).solve(depth), idx}).ToList().OrderBy(v=>v.idx).Select(v=>v.s).ToArray();
            for (int j = 0; j < sols.Length; j++)
            {
                string k1 = sols[j];
                count += k1.Length;
                int k = i + j;
                int estimate = (int)((count*(long)tests.Length)/(k+1));
                Console.WriteLine(k + "\t" + start.Elapsed.TotalMinutes.ToString("F2") + "\t" + count + "\t" + estimate + "\t" + k1.Length + "\t" + k1);
            }
        }
        Console.WriteLine(count);
    }
}

public class Solver2
{
    public readonly int MAX_DIM;
    public char[] board;
    public Solver2(string prob)
    {
        board = read(prob);
        MAX_DIM = (int)Math.Sqrt(board.Length);
    }

    public string solve(int d)
    {
        string best = null;
        for (int k = d; k >= 1; k--)
        {
            string c = subSolve(k);
            if (best == null || c.Length < best.Length)
                best = c;
        }
        return best;
    }

    public string subSolve(int d)
    {
        State current = new State(copy(board), '\0', flood(board));
        var sol = "";

        while (current.score != board.Length)
        {
            State nextState = subSolve(current, d);
            sol = sol + nextState.key;
            current = nextState;
        }
        return sol;
    }

    public State subSolve(State baseState, int d)
    {
        if (d == 0)
            return baseState;
        if (!baseState.childrenGenerated)
        {
            for (int i = 0; i < baseState.children.Length; i++)
            {
                if (('1' + i) == baseState.key) continue; //no point in even eval'ing
                char[] board = copy(baseState.board);
                foreach(int idx in baseState.flood)
                    board[idx] = (char)('1' + i);
                List<int> f = flood(board);
                if (f.Count != baseState.score)
                    baseState.children[i] = new State(board, (char)('1' + i), f);
            }
            baseState.childrenGenerated = true;
        }
        State bestState = null;

        for (int i = 0; i < baseState.children.Length; i++)
            if (baseState.children[i] != null)
            {
                State bestChild = subSolve(baseState.children[i], d - 1);
                baseState.children[i].bestChildScore = bestChild.bestChildScore;
                if (bestState == null || bestState.bestChildScore < bestChild.bestChildScore)
                    bestState = baseState.children[i];
            }
        if (bestState == null || bestState.bestChildScore == baseState.score)
        {
            if (baseState.score == baseState.board.Length)
                baseState.bestChildScore = baseState.score*(d + 1);
            return baseState;
        }
        return bestState;
    }

    public char[] read(string s)
    {
        return s.Where(c => c >= '1' && c <= '6').ToArray();
    }

    public char[] copy(char[] b)
    {
        char[] n = new char[b.Length];
        for (int i = 0; i < b.Length; i++)
            n[i] = b[i];
        return n;
    }

    public List<int> flood(char[] b)
    {
        int start = (MAX_DIM * (MAX_DIM / 2)) + (MAX_DIM / 2);
        var check = new List<int>(MAX_DIM * MAX_DIM);
        bool[] seen = new bool[b.Length];
        var hits = new List<int>(MAX_DIM * MAX_DIM);

        check.Add(start);
        seen[start] = true;
        char target = b[start];

        int at = 0;
        while (at < check.Count)
        {
            int toCheck = check[at++];
            if (b[toCheck] == target)
            {
                addNeighbors(check, seen, toCheck);
                hits.Add(toCheck);
            }
        }
        return hits;
    }

    public void addNeighbors(List<int> check, bool[] seen, int loc)
    {
        //int x = loc / MAX_DIM;
        int y = loc % MAX_DIM;

        if(loc+MAX_DIM < seen.Length)
            addNeighbor(check, seen, loc+MAX_DIM);
        if(loc-MAX_DIM >= 0)
            addNeighbor(check, seen, loc-MAX_DIM);
        if(y<MAX_DIM-1)
            addNeighbor(check, seen, loc+1);
        if (y > 0)
            addNeighbor(check, seen, loc-1);
    }

    public void addNeighbor(List<int> check, bool[] seen, int l)
    {
        if (!seen[l])
        {
            seen[l] = true;
            check.Add(l);
        }
    }
}

public class State
{
    public readonly char[] board;
    public readonly char key;
    public readonly State[] children = new State[6];
    public readonly List<int> flood; 
    public readonly int score;
    public bool childrenGenerated;
    public int bestChildScore;
    public State(char[] board, char k, List<int> flood)
    {
        this.board = board;
        key = k;
        this.flood = flood;
        score = flood.Count;
        bestChildScore = score;
    }
}

Delphi XE3 2,979,145个步骤

好的，这是我的尝试。我将变化的部分称为斑点，每转一圈都会制作一个数组的副本，并测试每种可能的颜色以查看哪种颜色会产生最大的斑点。

在3小时6分钟内运行所有拼图

program Main;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  SysUtils,
  Classes,
  Generics.Collections,
  math,
  stopwatch in 'stopwatch.pas';

type
  myArr=array[0..1]of integer;
const
  MaxSize=19;
  puzLoc='here is my file';
var
  L:TList<TList<integer>>;
  puzzles:TStringList;
  sc:TList<myArr>;
  a:array[0..MaxSize-1,0..MaxSize-1] of Integer;
  aTest:array[0..MaxSize-1,0..MaxSize-1] of Integer;
  turns,midCol,sX,sY,i:integer;
  currBlob,biggestBlob,ColorBigBlob:integer;
  sTurn:string='';
  GLC:integer=0;

procedure FillArrays;
var
  ln,x,y:integer;
  puzzle:TStringList;
begin
  sc:=TList<myArr>.Create;
  puzzle:=TStringList.Create;    
  while puzzle.Count<19 do
  begin
    if puzzles[GLC]='' then
    begin
      inc(GLC);
      continue
    end
    else
      puzzle.Add(puzzles[GLC]);
    inc(GLC)
  end;    
  for y:=0to MaxSize-1do
    for x:=0to MaxSize-1do
      a[y][x]:=Ord(puzzle[y][x+1])-48;
  puzzle.Free;
end;
function CreateArr(nx,ny:integer):myArr;
begin
  Result[1]:=nx;
  Result[0]:=ny;
end;

procedure CreateBlob;
var
  tst:myArr;
  n,tx,ty:integer;
  currColor:integer;
begin
  n:=0;
  sc.Clear;
  currColor:=a[sy][sx];
  sc.Add(CreateArr(sx,sy));
  repeat
    tx:=sc[n][1];
    ty:=sc[n][0];
    if tx>0 then
      if a[ty][tx-1]=currColor then
      begin
        tst:=CreateArr(tx-1,ty);
        if not sc.Contains(tst)then
          sc.Add(tst);
      end;
    if tx<MaxSize-1 then
      if a[ty][tx+1]=currColor then
      begin
        tst:=CreateArr(tx+1,ty);
        if not sc.Contains(tst)then
          sc.Add(tst);
      end;
    if ty>0 then
      if a[ty-1][tx]=currColor then
      begin
        tst:=CreateArr(tx,ty-1);
        if not sc.Contains(tst)then
          sc.Add(tst);
      end;
    if ty<MaxSize-1 then
      if a[ty+1][tx]=currColor then
      begin
        tst:=CreateArr(tx,ty+1);
        if not sc.Contains(tst)then
          sc.Add(tst);
      end;
    inc(n);
  until (n=sc.Count);
end;

function BlobSize:integer;
var
  L:TList<myArr>;
  tst:myArr;
  n,currColor,tx,ty:integer;
begin
  n:=0;
  L:=TList<myArr>.Create;
  currColor:=aTest[sy][sx];
  L.Add(CreateArr(sx,sy));

  repeat
    tx:=L[n][1];
    ty:=L[n][0];
    if tx>0then
      if aTest[ty][tx-1]=currColor then
      begin
        tst:=CreateArr(tx-1,ty);
        if not L.Contains(tst)then
          L.Add(tst);
      end;
    if tx<MaxSize-1then
      if aTest[ty][tx+1]=currColor then
      begin
        tst:=CreateArr(tx+1,ty);
        if not L.Contains(tst)then
          L.Add(tst);
      end;
    if ty>0then
      if aTest[ty-1][tx]=currColor then
      begin
        tst:=CreateArr(tx,ty-1);
        if not L.Contains(tst)then
          L.Add(tst);
      end;
    if ty<MaxSize-1then
      if aTest[ty+1][tx]=currColor then
      begin
        tst:=CreateArr(tx,ty+1);
        if not L.Contains(tst)then
          L.Add(tst);
      end;
    inc(n);
  until n=l.Count;
  Result:=L.Count;
  L.Free;
end;

function AllsameColor(c:integer):boolean;
var
  cy,cx:integer;
begin
  Result:=true;
  for cy:=0to MaxSize-1do
    for cx:=0to MaxSize-1do
      if a[cy][cx]=c then
        continue
      else
        exit(false);
end;
procedure ChangeColors(old,new:integer; testing:boolean=false);
var
  i,j:integer;
  tst:myArr;
begin
  if testing then
  begin
    for i:= 0to MaxSize-1do
      for j:= 0to MaxSize-1do
        aTest[i][j]:=a[i][j];    
    for I:=0to sc.Count-1do
    begin
      tst:=sc[i];
      aTest[tst[0]][tst[1]]:=new;
    end;
  end
  else
  begin
    for I:=0to sc.Count-1do
    begin
      tst:=sc[i];
      a[tst[0]][tst[1]]:=new;
    end;
  end;
end;
var
  sw, swTot:TStopWatch;
  solved:integer=0;
  solutions:TStringList;
  steps:integer;
  st:TDateTime;
begin          
  st:=Now;
  writeln(FormatDateTime('hh:nn:ss',st));
  solutions:=TStringList.Create;
  puzzles:=TStringList.Create;
  puzzles.LoadFromFile(puzLoc);
  swTot:=TStopWatch.Create(true);
  turns:=0;
  repeat
    sTurn:='';    
    FillArrays;
    sX:=Round(Sqrt(MaxSize))+1;
    sY:=sX;    
    repeat
      biggestBlob:=0;
      ColorBigBlob:=0;
      midCol:=a[sy][sx];
      CreateBlob;
      for I:=1to 6do
      begin
        if I=midCol then continue;    
        ChangeColors(midCol,I,true);
        currBlob:=BlobSize;
        if currBlob>biggestBlob then
        begin
          biggestBlob:=currBlob;
          ColorBigBlob:=i;
        end;
      end;
      ChangeColors(midCol,ColorBigBlob);
      inc(turns);
      if sTurn='' then
        sTurn:=IntToStr(ColorBigBlob)
      else
        sTurn:=sTurn+', '+IntToStr(ColorBigBlob);
    until AllsameColor(a[sy][sx]);
    solutions.Add(sTurn);
    inc(solved);
    if solved mod 100=0then
      writeln(Format('Solved %d puzzles || %s',[solved,FormatDateTime('hh:nn:ss',Now-st)]));    
  until GLC>=puzzles.Count-1;    
  swTot.Stop;
  WriteLn(Format('solving these puzzles took %d',[swTot.Elapsed]));
  writeln(Format('Total moves: %d',[turns]));
  solutions.SaveToFile('save solutions here');
  readln;
end.

也考虑暴力破解回溯方法。
也许这个周末很有趣^^

Javascript / node.js-2,588,847

算法与此处的大多数算法有所不同，因为它利用了预先计算的区域和计算之间的差异状态。如果您因为javascript而担心速度，它可以在10分钟内运行。

var fs = require('fs')


var file = fs.readFileSync('floodtest','utf8');
var boards = file.split('\n\n');
var linelength  = boards[0].split('\n')[0].length;
var maxdim = linelength* linelength;


var board = function(info){
    this.info =[];
    this.sameNeighbors = [];
    this.differentNeighbors = [];
    this.samedifferentNeighbors = [];
    for (var i = 0;i <info.length;i++ ){
        this.info.push(info[i]|0);
    };

    this.getSameAndDifferentNeighbors();
}

board.prototype.getSameAndDifferentNeighbors = function(){
    var self = this;
    var info = self.info;
    function getSameNeighbors(i,value,sameneighbors,diffneighbors){

        var neighbors = self.getNeighbors(i);
        for(var j =0,nl = neighbors.length; j< nl;j++){
            var index = neighbors[j];
            if (info[index]  === value ){
                if( sameneighbors.indexOf(index) === -1){
                    sameneighbors.push(index);
                    getSameNeighbors(index,value,sameneighbors,diffneighbors);
                }
            }else if( diffneighbors.indexOf(index) === -1){
                    diffneighbors.push(index);
            }
        } 

    }


    var sneighbors = [];
    var dneighbors = [];
    var sdneighbors = [];

    for(var i= 0,l= maxdim;i<l;i++){
        if (sneighbors[i] === undefined){
            var sameneighbors = [i];
            var diffneighbors = [];
            getSameNeighbors(i,info[i],sameneighbors,diffneighbors);
            for (var j = 0; j<sameneighbors.length;j++){
                var k = sameneighbors[j];
                sneighbors[k] = sameneighbors;
                dneighbors[k] = diffneighbors;
            } 
        }

    }

    for(var i= 0,l= maxdim;i<l;i++){
        if (sdneighbors[i] === undefined){
            var value = [];
            var dni = dneighbors[i];
            for (var j = 0,dnil = dni.length; j<dnil;j++){
                var dnij = dni[j];
                var sdnij = sneighbors[dnij];
                for(var k = 0,sdnijl = sdnij.length;k<sdnijl;k++){
                    if (value.indexOf(sdnij[k])=== -1){
                        value.push(sdnij[k]);
                    }
                }
            };
            var sni = sneighbors[i];
            for (var j=0,snil = sni.length;j<snil;j++){
                sdneighbors[sni[j]] = value;
            };
        };
    }
    this.sameNeighbors = sneighbors;
    this.differentNeighbors =  dneighbors;
    this.samedifferentNeighbors =sdneighbors;

}

board.prototype.getNeighbors = function(i){
        var returnValue = [];

        var index = i-linelength;
        if (index >= 0){
            returnValue.push(index);
        }

        index = i+linelength;
        if (index < maxdim){

            returnValue.push(index);
        }

        index = i-1;

        if (index >= 0 && index/linelength >>> 0 === i/linelength  >>> 0){
            returnValue.push(index);
        }
        index = i+1;
        if (index/linelength >>> 0 === i/linelength >>> 0){
            returnValue.push(index);
        }

        if (returnValue.indexOf(-1) !== -1){
            console.log(i,parseInt(index/linelength,10),parseInt(i/linelength,10));
        } 
        return returnValue 
}

board.prototype.solve = function(){
    var i,j;
    var info = this.info;
    var sameNeighbors = this.sameNeighbors;
    var samedifferentNeighbors = this.samedifferentNeighbors;
    var middle = 9*19+9;
    var maxValues = [];

    var done = {};
    for (i=0; i<sameNeighbors[middle].length;i++){
        done[sameNeighbors[middle][i]] = true;
    }
    var usefullNeighbors = [[],[],[],[],[],[],[]];
    var diff = [];
    var count = [0];

    count[1] = 0;
    count[2] = 0;
    count[3] = 0;
    count[4] = 0;
    count[5] = 0;
    count[6] = 0;

    var addusefullNeighbors = function(index,diff){

        var indexsamedifferentNeighbors =samedifferentNeighbors[index];
        for (var i=0;i < indexsamedifferentNeighbors.length;i++){
            var is = indexsamedifferentNeighbors[i];
            var value = info[is];
            if (done[is] === undefined && usefullNeighbors[value].indexOf(is) === -1){
                usefullNeighbors[value].push(is);
                diff.push(value);
            }

        }
    }
    addusefullNeighbors(middle,diff);


    while(  usefullNeighbors[1].length > 0 || usefullNeighbors[2].length > 0 ||
            usefullNeighbors[3].length > 0 || usefullNeighbors[4].length > 0 ||
            usefullNeighbors[5].length > 0 || usefullNeighbors[6].length > 0 ){
        for (i=0;i < diff.length;i++){ 
            count[diff[i]]++;
        };
        var maxValue = count.indexOf(Math.max.apply(null, count));
        diff.length = 0;
        var used = usefullNeighbors[maxValue];
        for (var i=0,ul = used.length;i < ul;i++){
            var index = used[i];
            if (info[index] === maxValue){
                done[index] = true;
                addusefullNeighbors(index,diff);
            }
        }
        used.length = 0;
        count[maxValue] = 0;


        maxValues.push(maxValue);
    }
    return maxValues.join("");
};
var solved = [];
var start = Date.now();
for (var boardindex =0;boardindex < boards.length;boardindex++){ 
    var b = boards[boardindex].replace(/\n/g,'').split('');
    var board2 = new board(b);
    solved.push(board2.solve());
};
var diff = Date.now()-start;
console.log(diff,boards.length);
console.log(solved.join('').length);
console.log("end");

fs.writeFileSync('solution.txt',solved.join('\n'),'utf8');

确保通过简单的蛮力找到最佳解决方案的C代码。适用于任意大小的网格和所有输入。在大多数网格上运行都需要非常非常长的时间。

洪水填充效率极低，并且依赖于递归。如果堆栈很小，则可能需要将其增大。蛮力系统使用字符串来保存数字，并使用简单的带进位加法来循环选择所有可能的选项。这也是极其无效的，因为它会重复大多数步骤四千万次。

不幸的是，我无法针对所有测试用例进行测试，因为我将在测试完成之前死于老年。

#include <stdio.h>
#include <string.h>


#define GRID_SIZE       19

char grid[GRID_SIZE][GRID_SIZE] = { {3,3,5,4,1,3,4,1,5,3,3,5,4,1,3,4,1,5},
                                    {5,1,3,4,1,1,5,2,1,3,3,5,4,1,3,4,1,5},
                                    {6,5,2,3,4,3,3,4,3,3,3,5,4,1,3,4,1,5},
                                    {4,4,4,5,5,5,4,1,4,3,3,5,4,1,3,4,1,5},
                                    {6,2,5,3,3,1,1,6,6,3,3,5,4,1,3,4,1,5},
                                    {5,5,1,2,5,2,6,6,3,3,3,5,4,1,3,4,1,5},
                                    {6,1,1,5,3,6,2,3,6,3,3,5,4,1,3,4,1,5},
                                    {1,2,2,4,5,3,5,1,2,3,3,5,4,1,3,4,1,5},
                                    {3,6,6,1,5,1,3,2,4,3,3,5,4,1,3,4,1,5} };
char grid_save[GRID_SIZE][GRID_SIZE];

char test_grids[6][GRID_SIZE][GRID_SIZE];

void flood_fill(char x, char y, char old_colour, char new_colour)
{
    if (grid[y][x] == new_colour)
        return;

    grid[y][x] = new_colour;

    if (y > 0)
    {
        if (grid[y-1][x] == old_colour)
            flood_fill(x, y-1, old_colour, new_colour);
    }
    if (y < GRID_SIZE - 1)
    {
        if (grid[y+1][x] == old_colour)
            flood_fill(x, y+1, old_colour, new_colour);
    }

    if (x > 0)
    {
        if (grid[y][x-1] == old_colour)
            flood_fill(x-1, y, old_colour, new_colour);
    }
    if (x < GRID_SIZE - 1)
    {
        if (grid[y][x+1] == old_colour)
            flood_fill(x+1, y, old_colour, new_colour);
    }
}

bool check_grid(void)
{
    for (char i = 0; i < 6; i++)
    {
        if (!memcmp(grid, &test_grids[i][0][0], sizeof(grid)))
            return(true);
    }

    return(false);
}

void inc_string_num(char *s)
{
    char *c;

    c = s + strlen(s) - 1;
    *c += 1;

    // carry
    while (*c > '6')
    {
        *c = '1';
        if (c == s) // first char
        {
            strcat(s, "1");
            return;
        }
        c--;
        *c += 1;
    }
}

void print_grid(void)
{
    char x, y;
    for (y = 0; y < GRID_SIZE; y++)
    {
        for (x = 0; x < GRID_SIZE; x++)
            printf("%d ", grid[y][x]);
        printf("\n");
    }
    printf("\n");
}

int main(int argc, char* argv[])
{
    // create test grids for comparisons
    for (char i = 0; i < 6; i++)
        memset(&test_grids[i][0][0], i+1, GRID_SIZE*GRID_SIZE);

    char s[256] = "0";
    //char s[256] = "123456123456123455";
    memcpy(grid_save, grid, sizeof(grid));


    print_grid();
    do
    {
        memcpy(grid, grid_save, sizeof(grid));
        inc_string_num(s);

        for (unsigned int i = 0; i < strlen(s); i++)
        {
            flood_fill(4, 4, grid[4][4], s[i] - '0');
        }
    } while(!check_grid());
    print_grid();

    printf("%s\n", s);

    return 0;
}

据我所知，这是目前的赢家。比赛要求：

您的程序必须完全具有确定性。允许使用伪随机解，但是程序每次必须为相同的测试用例生成相同的输出。

校验

获胜的程序将以最少的步骤总数来解决此文件（压缩文本文件，14.23 MB）中找到的所有100,000个测试用例。如果两个解决方案采用相同数量的步骤（例如，如果它们都找到了最佳策略），则较短的程序将获胜。

由于这总是找到完成每个电路板所需的最少步骤，而其他任何步骤都没有，因此目前处于领先地位。如果有人可以提出一个较短的程序，那么他们可能会获胜，所以我提出以下尺寸优化的版本。执行速度稍慢一些，但是执行时间并不是获胜条件的一部分：

#include <stdio.h>
#include <string.h>
#define A 9
int g[A][A]={{3,3,5,4,1,3,4,1,5},{5,1,3,4,1,1,5,2,1},{6,5,2,3,4,3,3,4,3},{4,4,4,5,5,5,4,1,4},{6,2,5,3,3,1,1,6,6},{5,5,1,2,5,2,6,6,3},{6,1,1,5,3,6,2,3,6},{1,2,2,4,5,3,5,1,2},{3,6,6,1,5,1,3,2,4}};
int s[A][A];
int t[6][A][A];
void ff(int x,int y,int o,int n)
{if (g[y][x]==n)return;g[y][x]=n;if (y>0){if(g[y-1][x]==o)ff(x,y-1,o,n);}if(y<A-1){if(g[y+1][x]==o)ff(x,y+1,o,n);}if(x>0){if (g[y][x-1] == o)ff(x-1,y,o,n);}if(x<A-1){if(g[y][x+1]==o)ff(x+1,y,o,n);}}
bool check_g(void)
{for(int i=0;i<6;i++){if(!memcmp(g,&t[i][0][0],sizeof(g)))return(true);}return(0);}
void is(char*s){char*c;c=s+strlen(s)-1;*c+=1;while(*c>'6'){*c='1';if (c==s){strcat(s,"1");return;}c--;*c+=1;}}
void pr(void)
{int x, y;for(y=0;y<A;y++){for(x=0;x<A;x++)printf("%d ",g[y][x]);printf("\n");}printf("\n");}
int main(void)
{for(int i=0;i<6;i++)memset(&t[i][0][0],i+1,A*A);char s[256]="0";memcpy(s,g,sizeof(g));pr();do{memcpy(g,s,sizeof(g));is(s);for(int i=0;i<strlen(s);i++){ff(4,4,g[4][4],s[i]-'0');}}while(!check_g());
pr();printf("%s\n",s);return 0;}