背景

毕达哥拉斯三角形是直角三角形，其中每个边的长度是一个整数（即，边的长度形成毕达哥拉斯三重）：

使用这个三角形的边，我们可以附加两个不完全一致的毕达哥拉斯三角形，如下所示：

只要我们认为合适，就可以继续使用此模式，只要没有两个三角形重叠并且连接边的长度相等即可：

问题是，在给定的空间中，我们可以容纳多少个非一致的毕达哥拉斯三角形？

输入

您将通过函数参数，STDIN，字符串或任何您喜欢的变量接收两个整数作为输入，W和H。整数可以以十进制，十六进制，二进制，一元（祝您好运，Retina）或任何其他整数基数形式接收。您可能会认为max(W, H) <= 2^15 - 1。

输出

您的程序或函数应计算一个不重叠的连接的非一致勾股勾勒三角形的列表，并输出一组三个坐标的列表，其中一组坐标通过线连接时形成勾股勾勒三角形之一。坐标必须是我们空间中的实数（x必须在区间中，[0, W]并且y必须在区间中[0, H]），并且距离应精确到机器精度。三角形的顺序和每个坐标的确切格式并不重要。

必须有可能从一个三角形“行走”到其他任何一个，仅跨过相连的边界。

使用上述图作为一个例子，让我们的输入是W = 60，H = 60。

然后，我们的输出可能是以下坐标列表：

(0, 15), (0, 21), (8, 15)
(0, 21), (14.4, 40.2), (8, 15)
(0, 15), (8, 0), (8, 15)
(8, 0), (8, 15), (28, 15)
(8, 15), (28, 15), (28, 36)
(28, 15), (28, 36), (56, 36)

现在，鉴于我们的空间，六个三角形肯定不是最好的。你能做得更好吗？

规则和计分

• 您对此挑战的得分是在输入的情况下您的程序生成的三角形数量W = 1000, H = 1000。如果我怀疑有人对此案件进行了硬编码，我保留更改此输入的权利。

• 您可能不会使用计算毕达哥拉斯三元组的内建函数，也可能不会对超过2个毕达哥拉斯三元组的列表进行硬编码（如果您对程序进行硬编码，使其始终以（3、4、5）三角形开头或类似的开始情况，没关系）。

• 您可以用任何语言编写提交的内容。鼓励可读性和评论。

• 您可以在此处找到勾股三元组的列表。

• 不允许使用标准漏洞。

Python 3、109

这无疑是一个看似困难的挑战。很多次编写代码时，我发现自己在质疑基本的几何能力。话虽如此，我对结果非常满意。我毫不费力地提出了一个复杂的算法来放置三角形，相反，我的代码总是通过总是放置可能找到的最小对象而大失所望。我希望以后可以改善此问题，否则我的答案会促使其他人寻找更好的算法！总而言之，这是一个非常有趣的问题，并且会生成一些有趣的图片。

这是代码：

import time
import math

W = int(input("Enter W: "))
H = int(input("Enter H: "))

middle_x = math.floor(W/2)
middle_y = math.floor(H/2)

sides = [ # each side is in the format [length, [x0, y0], [x1, y1]]
    [3,[middle_x,middle_y],[middle_x+3,middle_y]],
    [4,[middle_x,middle_y],[middle_x,middle_y+4]],
    [5,[middle_x+3,middle_y],[middle_x,middle_y+4]]
    ]

triangles = [[0,1,2]] # each triangle is in the format [a, b, c] where a, b and c are the indexes of sides

used_triangles = [[3,4,5]] # a list of used Pythagorean triples, where lengths are ordered (a < b < c)

max_bounds_length = math.sqrt(W**2 + H**2)

def check_if_pyth_triple(a,b): # accepts two lists of the form [l, [x0,y0], [x1,y1]] defining two line segments
    # returns 0 if there are no triples, 1 if there is a triple with a right angle on a,
    # and 2 if there is a triple with the right angle opposite a
    c = math.sqrt(a[0]**2 + b[0]**2)
    if c.is_integer():
        if not sorted([a[0], b[0], c]) in used_triangles:
            return 1
        return 0
    else:
        if a[0] > b[0]:
            c = math.sqrt(a[0]**2 - b[0]**2)
            if c.is_integer() and not sorted([a[0], b[0], c]) in used_triangles:
                return 2
        return 0

def check_if_out_of_bounds(p):
    out = False
    if p[0] < 0 or p[0] > W:
        out = True
    if p[1] < 0 or p[1] > H:
        out = True
    return out

def in_between(a,b,c):
    maxi = max(a,c)
    mini = min(a,c)
    return mini < b < maxi

def sides_intersect(AB,CD): # accepts two lists of the form [l, [x0,y0], [x1,y1]] defining two line segments
    # doesn't count overlapping lines
    A = AB[1]
    B = AB[2]
    C = CD[1]
    D = CD[2]

    if A[0] == B[0]: # AB is vertical
        if C[0] == D[0]: # CD is vertical
            return False
        else:
            m1 = (C[1] - D[1])/(C[0] - D[0]) # slope of CD
            y = m1*(A[0] - C[0]) + C[1] # the y value of CD at AB's x value
            return in_between(A[1], y, B[1]) and in_between(C[0], A[0], D[0])
    else:
        m0 = (A[1] - B[1])/(A[0] - B[0]) # slope of AB
        if C[0] == D[0]: # CD is vertical
            y = m0*(C[0] - A[0]) + A[1] # the y value of CD at AB's x value
            return in_between(C[1], y, D[1]) and in_between(A[0],C[0],B[0])
        else:
            m1 = (C[1] - D[1])/(C[0] - D[0]) # slope of CD
            if m0 == m1:
                return False
            else:
                x = (m0*A[0] - m1*C[0] - A[1] + C[1])/(m0 - m1)
                return in_between(A[0], x, B[0]) and in_between(C[0], x, D[0])

def check_all_sides(b,triangle):
    no_intersections = True
    for side in sides:
        if sides_intersect(side, b):
            no_intersections = False
            break

    return no_intersections

def check_point_still_has_room(A): # This function is needed for the weird case when all 2pi degrees
    # around a point are filled by triangles, but you could fit in a small triangle into another one
    # already built around the point. Doing this won't cause sides_intersect() to detect it because
    # the sides will all be parallel. Crazy stuff.
    connecting_sides = []
    for side in sides:
        if A in side:
            connecting_sides.append(side)

    match_count = 0
    slopes = []
    for side in connecting_sides:
        B = side[1]
        if A == B:
            B = side[2]
        if not A[0] == B[0]:
            slope = round((A[1]-B[1])/(A[0]-B[0]),4)
        else:
            if A[1] < B[1]:
                slope = "infinity"
            else:
                slope = "neg_infinity"
        if slope in slopes:
            match_count -= 1
        else:
            slopes.append(slope)
            match_count += 1

    return match_count != 0

def construct_b(a,b,pyth_triple_info,straight_b_direction,bent_b_direction):
    # this function finds the correct third point of the triangle given a and the length of b
    # pyth_triple_info determines if a is a leg or the hypotenuse
    # the b_directions determine on which side of a the triangle should be formed
    a_p = 2 # this is the index of the point in a that is not the shared point with b
    if a[1] != b[1]:
        a_p = 1

    vx = a[a_p][0] - b[1][0] # v is our vector, and these are the coordinates, adjusted so that
    vy = a[a_p][1] - b[1][1] # the shared point is the origin

    if pyth_triple_info == 1:
        # because the dot product of orthogonal vectors is zero, we can use that and the Pythagorean formula
        # to get this simple formula for generating the coordinates of b's second point
        if vy == 0:
            x = 0
            y = b[0]
        else:
            x = b[0]/math.sqrt(1+((-vx/vy)**2)) # b[0] is the desired length
            y = -vx*x/vy

        x = x*straight_b_direction # since the vector is orthagonal, if we want to reverse the direction,
        y = y*straight_b_direction # it just means finding the mirror point

    elif pyth_triple_info == 2: # this finds the intersection of the two circles of radii b[0] and c 
        # around a's endpoints, which is the third point of the triangle if a is the hypotenuse
        c = math.sqrt(a[0]**2 - b[0]**2)
        D = a[0]
        A = (b[0]**2 - c**2 + D**2 ) / (2*D)
        h = math.sqrt(b[0]**2 - A**2)
        x2 = vx*(A/D)
        y2 = vy*(A/D)        
        x = x2 + h*vy/D
        y = y2 - h*vx/D

        if bent_b_direction == -1: # this constitutes reflection of the vector (-x,-y) around the normal vector n,
            # which accounts for finding the triangle on the opposite side of a
            dx = -x
            dy = -y
            v_length = math.sqrt(vx**2 + vy**2)
            nx = vx/v_length
            ny = vy/v_length

            d_dot_n = dx*nx + dy*ny

            x = dx - 2*d_dot_n*nx
            y = dy - 2*d_dot_n*ny

    x = x + b[1][0] # adjust back to the original frame
    y = y + b[1][1]

    return [x,y]

def construct_triangle(side_index):
    a = sides[side_index] # a is the base of the triangle
    a_p = 1
    b = [1, a[a_p], []] # side b, c is hypotenuse

    for index, triangle in enumerate(triangles):
        if side_index in triangle:
            triangle_index = index
            break

    triangle = list(triangles[triangle_index])
    triangle.remove(side_index)

    add_tri = False

    straight_b = construct_b(a,b,1,1,1)

    bent_b = construct_b(a,b,2,1,1)

    A = sides[triangle[0]][1]
    if A in a:
        A = sides[triangle[0]][2]

    Ax = A[0] - b[1][0] # adjusting A so that it's a vector
    Ay = A[1] - b[1][1]

    # these are for determining if construct_b() is going to the correct side
    triangle_on_side = (a[2][0]-a[1][0])*(A[1]-a[1][1]) - (a[2][1]-a[1][1])*(A[0]-a[1][0])
    straight_b_on_side = (a[2][0]-a[1][0])*(straight_b[1]-a[1][1]) - (a[2][1]-a[1][1])*(straight_b[0]-a[1][0])
    bent_b_on_side = (a[2][0]-a[1][0])*(bent_b[1]-a[1][1]) - (a[2][1]-a[1][1])*(bent_b[0]-a[1][0])

    straight_b_direction = 1
    if (triangle_on_side > 0 and straight_b_on_side > 0) or (triangle_on_side < 0 and straight_b_on_side < 0):
        straight_b_direction = -1

    bent_b_direction = 1
    if (triangle_on_side > 0 and bent_b_on_side > 0) or (triangle_on_side < 0 and bent_b_on_side < 0):
        bent_b_direction = -1


    a_ps = []
    for x in [1,2]:
        if check_point_still_has_room(a[x]): # here we check for that weird exception
            a_ps.append(x)

    while True:
        out_of_bounds = False
        if b[0] > max_bounds_length:
            break

        pyth_triple_info = check_if_pyth_triple(a,b)

        for a_p in a_ps:
            if a_p == 1: # this accounts for the change in direction when switching a's points
                new_bent_b_direction = bent_b_direction
            else:
                new_bent_b_direction = -bent_b_direction

            b[1] = a[a_p]
            if pyth_triple_info > 0:
                b[2] = construct_b(a,b,pyth_triple_info,straight_b_direction,new_bent_b_direction)

                if check_if_out_of_bounds(b[2]): # here is the check to make sure we don't go out of bounds
                    out_of_bounds = True
                    break

                if check_all_sides(b,triangle):
                    if pyth_triple_info == 1:
                        c = [math.sqrt(a[0]**2 + b[0]**2), a[3-a_p], b[2]]
                    else:
                        c = [math.sqrt(a[0]**2 - b[0]**2), a[3-a_p], b[2]]

                    if check_all_sides(c,triangle):
                        add_tri = True
                        break

        if out_of_bounds or add_tri:
            break

        b[0] += 1 # increment the length of b every time the loop goes through

    if add_tri: # this adds a new triangle
        sides.append(b)
        sides.append(c)
        sides_len = len(sides)
        triangles.append([side_index, sides_len - 2, sides_len - 1])
        used_triangles.append(sorted([a[0], b[0], c[0]])) # so we don't use the same triangle again

def build_all_triangles(): # this iterates through every side to see if a new triangle can be constructed
    # this is probably where real optimization would take place so more optimal triangles are placed first
    t0 = time.clock()

    index = 0
    while index < len(sides):
        construct_triangle(index)
        index += 1

    t1 = time.clock()

    triangles_points = [] # this is all for printing points
    for triangle in triangles:
        point_list = []
        for x in [1,2]:
            for side_index in triangle:
                point = sides[side_index][x]
                if not point in point_list:
                    point_list.append(point)
        triangles_points.append(point_list)

    for triangle in triangles_points:
        print(triangle)

    print(len(triangles), "triangles placed in", round(t1-t0,3), "seconds.")

def matplotlib_graph(): # this displays the triangles with matplotlib
    import pylab as pl
    import matplotlib.pyplot as plt
    from matplotlib import collections as mc

    lines = []
    for side in sides:
        lines.append([side[1],side[2]])

    lc = mc.LineCollection(lines)
    fig, ax = pl.subplots()
    ax.add_collection(lc)
    ax.autoscale()
    ax.margins(0.1)
    plt.show()

build_all_triangles()

下面是输出的图形W = 1000，并H = 1000与109个三角形：

这里是W = 10000和H = 10000724个三角形：

之后调用matplotlib_graph()函数build_all_triangles()以绘制三角形。

我觉得代码运行速度相当快：在W = 1000和H = 1000它需要0.66秒，并W = 10000和H = 10000它用我蹩脚的笔记本电脑需要45秒。

C ++，146个三角形（1/2部分）

结果为图像

算法说明

这使用了解决方案空间的广度优先搜索。在每个步骤中，它都从k适合该框的三角形的所有唯一配置开始，并k + 1通过枚举将未使用的三角形添加到任何配置的所有选项来构建三角形的所有唯一配置。

该算法的基本设置是使用穷尽的BFS查找绝对最大值。对于较小的尺寸，它可以成功做到这一点。例如，对于50x50的盒子，它会在大约1分钟内找到最大值。但是对于1000x1000，解决方案空间太大。为了终止它，我在每个步骤之后都会整理解决方案列表。保留的解决方案数由命令行参数指定。对于上述解决方案，使用的值为50。这导致大约10分钟的运行时间。

主要步骤的概要如下所示：

1. 生成所有可能适合框内的勾股三角。
2. 生成由每个具有1个三角形的解组成的初始解集。
3. 循环遍历（三角形计数）。
   1. 从解决方案集中消除无效的解决方案。这些解决方案要么不适合放在盒子里，要么重叠。
   2. 如果解决方案集为空，则完成。上一代解决方案集包含最大值。
   3. 如果启用了修剪选项，则将修剪解决方案设置为给定的大小。
   4. 循环浏览当前一代中的所有解决方案。
      1. 在解决方案的周长上遍历所有面。
         1. 查找边长与周长匹配的所有三角形，但尚未在解决方案中。
         2. 生成通过添加三角形产生的新解，并将解添加到新一代解中。
4. 打印解决方案。

整个方案的一个关键方面是配置通常会多次生成，而我们只对唯一配置感兴趣。因此，我们需要一个定义解决方案的唯一键，该键必须与生成解决方案时使用的三角形的顺序无关。例如，对键使用坐标根本不起作用，因为如果我们以多个顺序获得相同的解决方案，则坐标可能完全不同。我使用的是全局列表中的一组三角形索引，以及一组定义三角形如何连接的“连接器”对象。因此，该键仅对拓扑进行编码，而与2D空间中的构造顺序和位置无关。

虽然更多的是实现方面，但并非完全无关紧要的另一部分是确定整个对象是否以及如何适合给定的框。如果您真的想突破界限，显然有必要让旋转适合盒子内部。

稍后，我将尝试在第2部分中向代码添加一些注释，以防有人想深入了解所有工作原理的细节。

结果以正式文本格式

(322.085, 641.587) (318.105, 641.979) (321.791, 638.602)
(318.105, 641.979) (309.998, 633.131) (321.791, 638.602)
(318.105, 641.979) (303.362, 639.211) (309.998, 633.131)
(318.105, 641.979) (301.886, 647.073) (303.362, 639.211)
(301.886, 647.073) (297.465, 638.103) (303.362, 639.211)
(301.886, 647.073) (280.358, 657.682) (297.465, 638.103)
(301.886, 647.073) (283.452, 663.961) (280.358, 657.682)
(301.886, 647.073) (298.195, 666.730) (283.452, 663.961)
(301.886, 647.073) (308.959, 661.425) (298.195, 666.730)
(301.886, 647.073) (335.868, 648.164) (308.959, 661.425)
(335.868, 648.164) (325.012, 669.568) (308.959, 661.425)
(308.959, 661.425) (313.666, 698.124) (298.195, 666.730)
(313.666, 698.124) (293.027, 694.249) (298.195, 666.730)
(313.666, 698.124) (289.336, 713.905) (293.027, 694.249)
(298.195, 666.730) (276.808, 699.343) (283.452, 663.961)
(335.868, 648.164) (353.550, 684.043) (325.012, 669.568)
(303.362, 639.211) (276.341, 609.717) (309.998, 633.131)
(276.808, 699.343) (250.272, 694.360) (283.452, 663.961)
(335.868, 648.164) (362.778, 634.902) (353.550, 684.043)
(362.778, 634.902) (367.483, 682.671) (353.550, 684.043)
(250.272, 694.360) (234.060, 676.664) (283.452, 663.961)
(362.778, 634.902) (382.682, 632.942) (367.483, 682.671)
(382.682, 632.942) (419.979, 644.341) (367.483, 682.671)
(419.979, 644.341) (379.809, 692.873) (367.483, 682.671)
(353.550, 684.043) (326.409, 737.553) (325.012, 669.568)
(353.550, 684.043) (361.864, 731.318) (326.409, 737.553)
(353.550, 684.043) (416.033, 721.791) (361.864, 731.318)
(416.033, 721.791) (385.938, 753.889) (361.864, 731.318)
(385.938, 753.889) (323.561, 772.170) (361.864, 731.318)
(385.938, 753.889) (383.201, 778.739) (323.561, 772.170)
(383.201, 778.739) (381.996, 789.673) (323.561, 772.170)
(323.561, 772.170) (292.922, 743.443) (361.864, 731.318)
(323.561, 772.170) (296.202, 801.350) (292.922, 743.443)
(250.272, 694.360) (182.446, 723.951) (234.060, 676.664)
(335.868, 648.164) (330.951, 570.319) (362.778, 634.902)
(330.951, 570.319) (381.615, 625.619) (362.778, 634.902)
(330.951, 570.319) (375.734, 565.908) (381.615, 625.619)
(330.951, 570.319) (372.989, 538.043) (375.734, 565.908)
(323.561, 772.170) (350.914, 852.648) (296.202, 801.350)
(323.561, 772.170) (362.438, 846.632) (350.914, 852.648)
(234.060, 676.664) (217.123, 610.807) (283.452, 663.961)
(217.123, 610.807) (249.415, 594.893) (283.452, 663.961)
(375.734, 565.908) (438.431, 559.733) (381.615, 625.619)
(382.682, 632.942) (443.362, 567.835) (419.979, 644.341)
(443.362, 567.835) (471.667, 606.601) (419.979, 644.341)
(323.561, 772.170) (393.464, 830.433) (362.438, 846.632)
(372.989, 538.043) (471.272, 556.499) (375.734, 565.908)
(372.989, 538.043) (444.749, 502.679) (471.272, 556.499)
(372.989, 538.043) (365.033, 521.897) (444.749, 502.679)
(443.362, 567.835) (544.353, 553.528) (471.667, 606.601)
(544.353, 553.528) (523.309, 622.384) (471.667, 606.601)
(544.353, 553.528) (606.515, 572.527) (523.309, 622.384)
(419.979, 644.341) (484.688, 697.901) (379.809, 692.873)
(444.749, 502.679) (552.898, 516.272) (471.272, 556.499)
(217.123, 610.807) (170.708, 516.623) (249.415, 594.893)
(484.688, 697.901) (482.006, 753.837) (379.809, 692.873)
(484.688, 697.901) (571.903, 758.147) (482.006, 753.837)
(419.979, 644.341) (535.698, 636.273) (484.688, 697.901)
(276.808, 699.343) (228.126, 812.299) (250.272, 694.360)
(228.126, 812.299) (185.689, 726.188) (250.272, 694.360)
(228.126, 812.299) (192.246, 829.981) (185.689, 726.188)
(393.464, 830.433) (449.003, 936.807) (362.438, 846.632)
(393.464, 830.433) (468.505, 926.625) (449.003, 936.807)
(416.033, 721.791) (471.289, 833.915) (385.938, 753.889)
(471.289, 833.915) (430.252, 852.379) (385.938, 753.889)
(350.914, 852.648) (227.804, 874.300) (296.202, 801.350)
(192.246, 829.981) (114.401, 834.898) (185.689, 726.188)
(114.401, 834.898) (155.433, 715.767) (185.689, 726.188)
(217.123, 610.807) (91.773, 555.523) (170.708, 516.623)
(91.773, 555.523) (141.533, 457.421) (170.708, 516.623)
(141.533, 457.421) (241.996, 407.912) (170.708, 516.623)
(141.533, 457.421) (235.365, 394.457) (241.996, 407.912)
(241.996, 407.912) (219.849, 525.851) (170.708, 516.623)
(241.996, 407.912) (304.896, 419.724) (219.849, 525.851)
(91.773, 555.523) (55.917, 413.995) (141.533, 457.421)
(571.903, 758.147) (476.260, 873.699) (482.006, 753.837)
(571.903, 758.147) (514.819, 890.349) (476.260, 873.699)
(571.903, 758.147) (587.510, 764.886) (514.819, 890.349)
(587.510, 764.886) (537.290, 898.778) (514.819, 890.349)
(587.510, 764.886) (592.254, 896.801) (537.290, 898.778)
(587.510, 764.886) (672.455, 761.831) (592.254, 896.801)
(55.917, 413.995) (113.819, 299.840) (141.533, 457.421)
(113.819, 299.840) (149.275, 293.604) (141.533, 457.421)
(544.353, 553.528) (652.112, 423.339) (606.515, 572.527)
(652.112, 423.339) (698.333, 461.597) (606.515, 572.527)
(535.698, 636.273) (651.250, 731.917) (484.688, 697.901)
(651.250, 731.917) (642.213, 756.296) (484.688, 697.901)
(304.896, 419.724) (299.444, 589.636) (219.849, 525.851)
(304.896, 419.724) (369.108, 452.294) (299.444, 589.636)
(304.896, 419.724) (365.965, 299.326) (369.108, 452.294)
(304.896, 419.724) (269.090, 347.067) (365.965, 299.326)
(114.401, 834.898) (0.942, 795.820) (155.433, 715.767)
(114.401, 834.898) (75.649, 947.412) (0.942, 795.820)
(192.246, 829.981) (124.489, 994.580) (114.401, 834.898)
(269.090, 347.067) (205.435, 217.901) (365.965, 299.326)
(205.435, 217.901) (214.030, 200.956) (365.965, 299.326)
(182.446, 723.951) (68.958, 600.078) (234.060, 676.664)
(182.446, 723.951) (32.828, 633.179) (68.958, 600.078)
(652.112, 423.339) (763.695, 288.528) (698.333, 461.597)
(763.695, 288.528) (808.220, 324.117) (698.333, 461.597)
(763.695, 288.528) (811.147, 229.162) (808.220, 324.117)
(652.112, 423.339) (627.572, 321.247) (763.695, 288.528)
(627.572, 321.247) (660.872, 244.129) (763.695, 288.528)
(652.112, 423.339) (530.342, 344.618) (627.572, 321.247)
(652.112, 423.339) (570.488, 453.449) (530.342, 344.618)
(627.572, 321.247) (503.633, 267.730) (660.872, 244.129)
(365.965, 299.326) (473.086, 450.157) (369.108, 452.294)
(365.965, 299.326) (506.922, 344.440) (473.086, 450.157)
(365.965, 299.326) (394.633, 260.827) (506.922, 344.440)
(394.633, 260.827) (537.381, 303.535) (506.922, 344.440)
(811.147, 229.162) (979.067, 234.338) (808.220, 324.117)
(698.333, 461.597) (706.660, 655.418) (606.515, 572.527)
(811.147, 229.162) (982.117, 135.385) (979.067, 234.338)
(982.117, 135.385) (999.058, 234.954) (979.067, 234.338)
(365.965, 299.326) (214.375, 186.448) (394.633, 260.827)
(811.147, 229.162) (803.145, 154.590) (982.117, 135.385)
(803.145, 154.590) (978.596, 102.573) (982.117, 135.385)
(214.375, 186.448) (314.969, 126.701) (394.633, 260.827)
(314.969, 126.701) (508.984, 192.909) (394.633, 260.827)
(314.969, 126.701) (338.497, 88.341) (508.984, 192.909)
(338.497, 88.341) (523.725, 138.884) (508.984, 192.909)
(338.497, 88.341) (359.556, 11.163) (523.725, 138.884)
(808.220, 324.117) (801.442, 544.012) (698.333, 461.597)
(801.442, 544.012) (739.631, 621.345) (698.333, 461.597)
(660.872, 244.129) (732.227, 78.877) (763.695, 288.528)
(660.872, 244.129) (644.092, 40.821) (732.227, 78.877)
(808.220, 324.117) (822.432, 544.659) (801.442, 544.012)
(660.872, 244.129) (559.380, 47.812) (644.092, 40.821)
(660.872, 244.129) (556.880, 242.796) (559.380, 47.812)
(556.880, 242.796) (528.882, 242.437) (559.380, 47.812)
(808.220, 324.117) (924.831, 449.189) (822.432, 544.659)
(924.831, 449.189) (922.677, 652.177) (822.432, 544.659)
(922.677, 652.177) (779.319, 785.836) (822.432, 544.659)
(779.319, 785.836) (696.630, 771.054) (822.432, 544.659)
(779.319, 785.836) (746.412, 969.918) (696.630, 771.054)
(779.319, 785.836) (848.467, 840.265) (746.412, 969.918)
(848.467, 840.265) (889.327, 872.428) (746.412, 969.918)
(746.412, 969.918) (619.097, 866.541) (696.630, 771.054)
(779.319, 785.836) (993.200, 656.395) (848.467, 840.265)
(993.200, 656.395) (935.157, 864.450) (848.467, 840.265)
(993.200, 656.395) (995.840, 881.379) (935.157, 864.450)
(338.497, 88.341) (34.607, 5.420) (359.556, 11.163)
(338.497, 88.341) (189.294, 204.357) (34.607, 5.420)
(189.294, 204.357) (158.507, 228.296) (34.607, 5.420)
(158.507, 228.296) (38.525, 230.386) (34.607, 5.420)
(158.507, 228.296) (41.694, 412.358) (38.525, 230.386)

码

有关代码，请参见第2部分。它分为两部分，以解决帖子大小的限制。

该代码在PasteBin上也可用。

C ++，146个三角形（第2/2部分）

从第1部分开始接续。该部分分为2部分，以解决帖子大小限制。

码

要添加的注释。

#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <sstream>
#include <iostream>

class Vec2 {
public:
    Vec2()
      : m_x(0.0f), m_y(0.0f) {
    }

    Vec2(float x, float y)
      : m_x(x), m_y(y) {
    }

    float x() const {
        return m_x;
    }

    float y() const {
        return m_y;
    }

    void normalize() {
        float s = 1.0f / sqrt(m_x * m_x + m_y * m_y);
        m_x *= s;
        m_y *= s;
    }

    Vec2 operator+(const Vec2& rhs) const {
        return Vec2(m_x + rhs.m_x, m_y + rhs.m_y);
    }

    Vec2 operator-(const Vec2& rhs) const {
        return Vec2(m_x - rhs.m_x, m_y - rhs.m_y);
    }

    Vec2 operator*(float s) const {
        return Vec2(m_x * s, m_y * s);
    }

private:
    float m_x, m_y;
};

static float cross(const Vec2& v1, const Vec2& v2) {
    return v1.x() * v2.y() - v1.y() * v2.x();
}

class Triangle {
public:
    Triangle()
      : m_sideLenA(0), m_sideLenB(0), m_sideLenC(0) {
    }

    Triangle(int sideLenA, int sideLenB, int sideLenC)
      : m_sideLenA(sideLenA),
        m_sideLenB(sideLenB),
        m_sideLenC(sideLenC) {
    }

    int getSideLenA() const {
        return m_sideLenA;
    }

    int getSideLenB() const {
        return m_sideLenB;
    }

    int getSideLenC() const {
        return m_sideLenC;
    }

private:
    int m_sideLenA, m_sideLenB, m_sideLenC;
};

class Connector {
public:
    Connector(int sideLen, int triIdx1, int triIdx2, bool flipped);

    bool operator<(const Connector& rhs) const;

    void print() const {
        std::cout << m_sideLen << "/" << m_triIdx1 << "/"
                  << m_triIdx2 << "/" << m_flipped << " ";
    }

private:
    int m_sideLen;
    int m_triIdx1, m_triIdx2;
    bool m_flipped;
};

typedef std::vector<Triangle> TriangleVec;
typedef std::multimap<int, int> SideMap;

typedef std::set<int> TriangleSet;
typedef std::set<Connector> ConnectorSet;

class SolutionKey {
public:
    SolutionKey() {
    }

    void init(int triIdx);
    void add(int triIdx, const Connector& conn);

    bool containsTriangle(int triIdx) const;
    int minTriangle() const;

    bool operator<(const SolutionKey& rhs) const;

    void print() const;

private:
    TriangleSet m_tris;
    ConnectorSet m_conns;
};

typedef std::map<SolutionKey, class SolutionData> SolutionMap;

class SolutionData {
public:
    SolutionData()
      : m_lastPeriIdx(0),
        m_rotAng(0.0f),
        m_xShift(0.0f), m_yShift(0.0f) {
    }

    void init(int triIdx);

    bool fitsInBox();
    bool selfOverlaps() const;

    void nextGeneration(
        const SolutionKey& key, bool useTrim, SolutionMap& rNewSols) const;

    void print() const;

private:
    void addTriangle(
        const SolutionKey& key, int periIdx, int newTriIdx,
        SolutionMap& rNewSols) const;

    std::vector<int> m_periTris;
    std::vector<int> m_periLens;
    std::vector<bool> m_periFlipped;
    std::vector<Vec2> m_periPoints;

    int m_lastPeriIdx;

    std::vector<Vec2> m_triPoints;

    float m_rotAng;
    float m_xShift, m_yShift;
};

static int BoxW  = 0;
static int BoxH  = 0;
static int BoxD2 = 0;

static TriangleVec AllTriangles;
static SideMap AllSides;

Connector::Connector(
    int sideLen, int triIdx1, int triIdx2, bool flipped)
  : m_sideLen(sideLen),
    m_flipped(flipped) {
    if (triIdx1 < triIdx2) {
        m_triIdx1 = triIdx1;
        m_triIdx2 = triIdx2;
    } else {
        m_triIdx1 = triIdx2;
        m_triIdx2 = triIdx1;
    }
}

bool Connector::operator<(const Connector& rhs) const {
    if (m_sideLen < rhs.m_sideLen) {
        return true;
    } else if (m_sideLen > rhs.m_sideLen) {
        return false;
    }

    if (m_triIdx1 < rhs.m_triIdx1) {
        return true;
    } else if (m_triIdx1 > rhs.m_triIdx1) {
        return false;
    }

    if (m_triIdx2 < rhs.m_triIdx2) {
        return true;
    } else if (m_triIdx2 > rhs.m_triIdx2) {
        return false;
    }

    return m_flipped < rhs.m_flipped;
}

void SolutionKey::init(int triIdx) {
    m_tris.insert(triIdx);
}

void SolutionKey::add(int triIdx, const Connector& conn) {
    m_tris.insert(triIdx);
    m_conns.insert(conn);
}

bool SolutionKey::containsTriangle(int triIdx) const {
    return m_tris.count(triIdx);
}

int SolutionKey::minTriangle() const {
    return *m_tris.begin();
}

bool SolutionKey::operator<(const SolutionKey& rhs) const {
    if (m_tris.size() < rhs.m_tris.size()) {
        return true;
    } else if (m_tris.size() > rhs.m_tris.size()) {
        return false;
    }

    TriangleSet::const_iterator triIt1 = m_tris.begin();
    TriangleSet::const_iterator triIt2 = rhs.m_tris.begin();
    while (triIt1 != m_tris.end()) {
        if (*triIt1 < *triIt2) {
           return true;
        } else if (*triIt2 < *triIt1) {
           return false;
        }
        ++triIt1;
        ++triIt2;
    }

    if (m_conns.size() < rhs.m_conns.size()) {
        return true;
    } else if (m_conns.size() > rhs.m_conns.size()) {
        return false;
    }

    ConnectorSet::const_iterator connIt1 = m_conns.begin();
    ConnectorSet::const_iterator connIt2 = rhs.m_conns.begin();
    while (connIt1 != m_conns.end()) {
        if (*connIt1 < *connIt2) {
           return true;
        } else if (*connIt2 < *connIt1) {
           return false;
        }
        ++connIt1;
        ++connIt2;
    }

    return false;
}

void SolutionKey::print() const {
    TriangleSet::const_iterator triIt = m_tris.begin();
    while (triIt != m_tris.end()) {
        std::cout << *triIt << " ";
        ++triIt;
    }
    std::cout << "\n";

    ConnectorSet::const_iterator connIt = m_conns.begin();
    while (connIt != m_conns.end()) {
        connIt->print();
        ++connIt;
    }
    std::cout << "\n";
}

void SolutionData::init(int triIdx) {
    const Triangle& tri = AllTriangles[triIdx];

    m_periTris.push_back(triIdx);
    m_periTris.push_back(triIdx);
    m_periTris.push_back(triIdx);

    m_periLens.push_back(tri.getSideLenB());
    m_periLens.push_back(tri.getSideLenC());
    m_periLens.push_back(tri.getSideLenA());

    m_periFlipped.push_back(false);
    m_periFlipped.push_back(false);
    m_periFlipped.push_back(false);

    m_periPoints.push_back(Vec2(0.0f, 0.0f));
    m_periPoints.push_back(Vec2(tri.getSideLenB(), 0.0f));
    m_periPoints.push_back(Vec2(0.0f, tri.getSideLenA()));

    m_triPoints = m_periPoints;

    m_periPoints.push_back(Vec2(0.0f, 0.0f));
}

bool SolutionData::fitsInBox() {
    int nStep = 8;
    float angInc = 0.5f * M_PI / nStep;

    for (;;) {
        bool mayFit = false;
        float ang = 0.0f;

        for (int iStep = 0; iStep <= nStep; ++iStep) {
            float cosAng = cos(ang);
            float sinAng = sin(ang);

            float xMin = 0.0f;
            float xMax = 0.0f;
            float yMin = 0.0f;
            float yMax = 0.0f;
            bool isFirst = true;

            for (int iPeri = 0; iPeri < m_periLens.size(); ++iPeri) {
                const Vec2& pt = m_periPoints[iPeri];
                float x = cosAng * pt.x() - sinAng * pt.y();
                float y = sinAng * pt.x() + cosAng * pt.y();

                if (isFirst) {
                    xMin = x;
                    xMax = x;
                    yMin = y;
                    yMax = y;
                    isFirst = false;
                } else {
                    if (x < xMin) {
                        xMin = x;
                    } else if (x > xMax) {
                        xMax = x;
                    }
                    if (y < yMin) {
                        yMin = y;
                    } else if (y > yMax) {
                        yMax = y;
                    }
                }
            }

            float w = xMax - xMin;
            float h = yMax - yMin;

            bool fits = false;
            if ((BoxW >= BoxH) == (w >= h)) {
                if (w <= BoxW && h <= BoxH) {
                    m_rotAng = ang;
                    m_xShift = 0.5f * BoxW - 0.5f * (xMax + xMin);
                    m_yShift = 0.5f * BoxH - 0.5f * (yMax + yMin);
                    return true;
                }
            } else {
                if (h <= BoxW && w <= BoxH) {
                    m_rotAng = ang + 0.5f * M_PI;
                    m_xShift = 0.5f * BoxW + 0.5f * (yMax + yMin);
                    m_yShift = 0.5f * BoxH - 0.5f * (xMax + xMin);
                    return true;
                }
            }

            w -= 0.125f * w * angInc * angInc + 0.5f * h * angInc;
            h -= 0.125f * h * angInc * angInc + 0.5f * w * angInc;

            if ((BoxW < BoxH) == (w < h)) {
                if (w <= BoxW && h <= BoxH) {
                    mayFit = true;
                }
            } else {
                if (h <= BoxW && w <= BoxH) {
                    mayFit = true;
                }
            }

            ang += angInc;
        }

        if (!mayFit) {
            break;
        }

        nStep *= 4;
        angInc *= 0.25f;
    }

    return false;
}

static bool intersects(
    const Vec2& p1, const Vec2& p2,
    const Vec2& q1, const Vec2& q2) {

    if (cross(p2 - p1, q1 - p1) * cross(p2 - p1, q2 - p1) > 0.0f) {
        return false;
    }

    if (cross(q2 - q1, p1 - q1) * cross(q2 - q1, p2 - q1) > 0.0f) {
        return false;
    }

    return true;
}

bool SolutionData::selfOverlaps() const {
    int periSize = m_periPoints.size();

    int triIdx = m_periTris[m_lastPeriIdx];
    const Triangle& tri = AllTriangles[triIdx];
    float offsScale = 0.0001f / tri.getSideLenC();

    const Vec2& pt1 = m_periPoints[m_lastPeriIdx];
    const Vec2& pt3 = m_periPoints[m_lastPeriIdx + 1];
    const Vec2& pt2 = m_periPoints[m_lastPeriIdx + 2];

    Vec2 pt1o = pt1 + ((pt2 - pt1) + (pt3 - pt1)) * offsScale;
    Vec2 pt2o = pt2 + ((pt1 - pt2) + (pt3 - pt2)) * offsScale;
    Vec2 pt3o = pt3 + ((pt1 - pt3) + (pt2 - pt3)) * offsScale;

    float xMax = m_periPoints[0].x();
    float yMax = m_periPoints[0].y();
    for (int iPeri = 1; iPeri < m_periLens.size(); ++iPeri) {
        if (m_periPoints[iPeri].x() > xMax) {
            xMax = m_periPoints[iPeri].x();
        }
        if (m_periPoints[iPeri].y() > yMax) {
            yMax = m_periPoints[iPeri].y();
        }
    }

    Vec2 ptOut(xMax + 0.3f, yMax + 0.7f);
    int nOutInter = 0;

    for (int iPeri = 0; iPeri < m_periLens.size(); ++iPeri) {
        int iNextPeri = iPeri + 1;
        if (iPeri == m_lastPeriIdx) {
            ++iNextPeri;
        } else if (iPeri == m_lastPeriIdx + 1) {
            continue;
        }

        if (intersects(
            m_periPoints[iPeri], m_periPoints[iNextPeri], pt1o, pt3o)) {
            return true;
        }

        if (intersects(
            m_periPoints[iPeri], m_periPoints[iNextPeri], pt2o, pt3o)) {
            return true;
        }

        if (intersects(
            m_periPoints[iPeri], m_periPoints[iNextPeri], pt3o, ptOut)) {
            ++nOutInter;
        }
    }

    return nOutInter % 2;
}

void SolutionData::nextGeneration(
    const SolutionKey& key, bool useTrim, SolutionMap& rNewSols) const
{
    int nPeri = m_periLens.size();
    for (int iPeri = (useTrim ? 0 : m_lastPeriIdx); iPeri < nPeri; ++iPeri) {
        int len = m_periLens[iPeri];
        SideMap::const_iterator itCand = AllSides.lower_bound(len);
        SideMap::const_iterator itCandEnd = AllSides.upper_bound(len);
        while (itCand != itCandEnd) {
            int candTriIdx = itCand->second;
            if (!key.containsTriangle(candTriIdx) &&
                candTriIdx > key.minTriangle()) {
                addTriangle(key, iPeri, candTriIdx, rNewSols);
            }
            ++itCand;
        }
    }
}

void SolutionData::print() const {
    float cosAng = cos(m_rotAng);
    float sinAng = sin(m_rotAng);

    int nPoint = m_triPoints.size();

    for (int iPoint = 0; iPoint < nPoint; ++iPoint) {
        const Vec2& pt = m_triPoints[iPoint];
        float x = cosAng * pt.x() - sinAng * pt.y() + m_xShift;
        float y = sinAng * pt.x() + cosAng * pt.y() + m_yShift;
        std::cout << "(" << x << ", " << y << ")";

        if (iPoint % 3 == 2) {
            std::cout << std::endl;
        } else {
            std::cout << " ";
        }
    }
}

void SolutionData::addTriangle(
    const SolutionKey& key, int periIdx, int newTriIdx,
    SolutionMap& rNewSols) const {

    int triIdx = m_periTris[periIdx];
    bool flipped = m_periFlipped[periIdx];
    int len = m_periLens[periIdx];

    Connector conn1(len, triIdx, newTriIdx, flipped);
    SolutionKey newKey1(key);
    newKey1.add(newTriIdx, conn1);
    bool isNew1 = (rNewSols.find(newKey1) == rNewSols.end());

    Connector conn2(len, triIdx, newTriIdx, !flipped);
    SolutionKey newKey2(key);
    newKey2.add(newTriIdx, conn2);
    bool isNew2 = (rNewSols.find(newKey2) == rNewSols.end());

    if (!(isNew1 || isNew2)) {
        return;
    }

    SolutionData data;

    int periSize = m_periLens.size();
    data.m_periTris.resize(periSize + 1);
    data.m_periLens.resize(periSize + 1);
    data.m_periFlipped.resize(periSize + 1);
    data.m_periPoints.resize(periSize + 2);
    for (int k = 0; k <= periIdx; ++k) {
        data.m_periTris[k] = m_periTris[k];
        data.m_periLens[k] = m_periLens[k];
        data.m_periFlipped[k] = m_periFlipped[k];
        data.m_periPoints[k] = m_periPoints[k];
    }
    for (int k = periIdx + 1; k < periSize; ++k) {
        data.m_periTris[k + 1] = m_periTris[k];
        data.m_periLens[k + 1] = m_periLens[k];
        data.m_periFlipped[k + 1] = m_periFlipped[k];
        data.m_periPoints[k + 1] = m_periPoints[k];
    }
    data.m_periPoints[periSize + 1] = m_periPoints[periSize];

    data.m_lastPeriIdx = periIdx;

    data.m_periTris[periIdx] = newTriIdx;
    data.m_periTris[periIdx + 1] = newTriIdx;

    int triSize = m_triPoints.size();
    data.m_triPoints.resize(triSize + 3);
    for (int k = 0; k < triSize; ++k) {
        data.m_triPoints[k] = m_triPoints[k];
    }

    const Triangle& tri = AllTriangles[newTriIdx];
    int lenA = tri.getSideLenA();
    int lenB = tri.getSideLenB();
    int lenC = tri.getSideLenC();

    const Vec2& pt1 = m_periPoints[periIdx];
    const Vec2& pt2 = m_periPoints[periIdx + 1];

    Vec2 v = pt2 - pt1;
    v.normalize();
    Vec2 vn(v.y(), -v.x());

    float dA = lenA;
    float dB = lenB;
    float dC = lenC;

    int len1 = 0, len2 = 0;
    Vec2 pt31, pt32;

    if (len == lenA) {
        len1 = lenB;
        len2 = lenC;
        pt31 = pt1 + vn * dB;
        pt32 = pt2 + vn * dB;
    } else if (len == lenB) {
        len1 = lenC;
        len2 = lenA;
        pt31 = pt2 + vn * dA;
        pt32 = pt1 + vn * dA;
    } else {
        len1 = lenA;
        len2 = lenB;
        pt31 = pt1 + v * (dA * dA / dC) + vn * (dA * dB / dC);
        pt32 = pt1 + v * (dB * dB / dC) + vn * (dA * dB / dC);
    }

    if (isNew1) {
        data.m_periLens[periIdx] = len1;
        data.m_periLens[periIdx + 1] = len2;
        data.m_periFlipped[periIdx] = false;
        data.m_periFlipped[periIdx + 1] = false;
        data.m_periPoints[periIdx + 1] = pt31;

        data.m_triPoints[triSize] = pt1;
        data.m_triPoints[triSize + 1] = pt31;
        data.m_triPoints[triSize + 2] = pt2;

        rNewSols.insert(std::make_pair(newKey1, data));
    }

    if (isNew2) {
        data.m_periLens[periIdx] = len2;
        data.m_periLens[periIdx + 1] = len1;
        data.m_periFlipped[periIdx] = true;
        data.m_periFlipped[periIdx + 1] = true;
        data.m_periPoints[periIdx + 1] = pt32;

        data.m_triPoints[triSize] = pt1;
        data.m_triPoints[triSize + 1] = pt32;
        data.m_triPoints[triSize + 2] = pt2;

        rNewSols.insert(std::make_pair(newKey2, data));
    }
}

static void enumerateTriangles() {
    for (int c = 2; c * c <= BoxD2; ++c) {
        for (int a = 1; 2 * a * a < c * c; ++a) {
            int b = static_cast<int>(sqrt(c * c - a * a) + 0.5f);
            if (a * a + b * b == c * c) {
                Triangle tri(a, b, c);

                int triIdx = AllTriangles.size();
                AllTriangles.push_back(Triangle(a, b, c));

                AllSides.insert(std::make_pair(a, triIdx));
                AllSides.insert(std::make_pair(b, triIdx));
                AllSides.insert(std::make_pair(c, triIdx));
            }
        }
    }
}

static void eliminateInvalid(SolutionMap& rSols) {
    SolutionMap::iterator it = rSols.begin();
    while (it != rSols.end()) {
        SolutionMap::iterator itNext = it;
        ++itNext;

        SolutionData& rSolData = it->second;

        if (!rSolData.fitsInBox()) {
            rSols.erase(it);
        } else if (rSolData.selfOverlaps()) {
            rSols.erase(it);
        }

        it = itNext;
    }
}

static void trimSolutions(SolutionMap& rSols, int trimCount) {
    if (trimCount >= rSols.size()) {
        return;
    }

    SolutionMap::iterator it = rSols.begin();
    for (int iTrim = 0; iTrim < trimCount; ++iTrim) {
        ++it;
    }

    rSols.erase(it, rSols.end());
}

static void nextGeneration(
    const SolutionMap& srcSols, bool useTrim, SolutionMap& rNewSols) {
    SolutionMap::const_iterator it = srcSols.begin();
    while (it != srcSols.end()) {
        const SolutionKey& solKey = it->first;
        const SolutionData& solData = it->second;
        solData.nextGeneration(solKey, useTrim, rNewSols);
        ++it;
    }
}

static void printSolutions(const SolutionMap& sols) {
    std::cout << std::fixed;
    std::cout.precision(3);

    SolutionMap::const_iterator it = sols.begin();
    while (it != sols.end()) {
        const SolutionKey& solKey = it->first;
        solKey.print();
        const SolutionData& solData = it->second;
        solData.print();
        std::cout << std::endl;
        ++it;
    }
}

int main(int argc, char* argv[]) {
    if (argc < 3) {
        std::cerr << "usage: " << argv[0] << " width height [trimCount]"
                  << std::endl;
        return 1;
    }

    std::istringstream streamW(argv[1]);
    streamW >> BoxW;
    std::istringstream streamH(argv[2]);
    streamH >> BoxH;

    int trimCount = 0;
    if (argc > 3) {
        std::istringstream streamTrim(argv[3]);
        streamTrim >> trimCount;
    }

    BoxD2 = BoxW * BoxW + BoxH * BoxH;

    enumerateTriangles();
    int nTri = AllTriangles.size();

    SolutionMap solGen[2];
    int srcGen = 0;

    for (int iTri = 0; iTri < nTri; ++iTri) {
        const Triangle& tri = AllTriangles[iTri];

        SolutionKey solKey;
        solKey.init(iTri);

        SolutionData solData;
        solData.init(iTri);

        solGen[srcGen].insert(std::make_pair(solKey, solData));
    }

    int level = 1;

    for (;;) {
        eliminateInvalid(solGen[srcGen]);
        std::cout << "level: " << level
                  << " solutions: " << solGen[srcGen].size() << std::endl;
        if (solGen[srcGen].empty()) {
            break;
        }

        if (trimCount > 0) {
            trimSolutions(solGen[srcGen], trimCount);
        }

        solGen[1 - srcGen].clear();
        nextGeneration(solGen[srcGen], trimCount > 0, solGen[1 - srcGen]);

        srcGen = 1 - srcGen;
        ++level;
    }

    printSolutions(solGen[1 - srcGen]);

    return 0;
}