这项挑战是对我们的传奇挑战作家（ Calvin's Hobbies）（现在更名为Helka Homba）的致敬，其精神与“ 生成丹尼斯数字 ”相同 。

卡尔文（Calvin）是PPCG的杰出贡献者，在整体声誉中名列第六，在我们所有人当中，毫无疑问，最佳挑战写作技能是无可争议的。但是，当然，对于这一挑战，我们将重点关注他的用户ID。

起初26997可能看起来不太有趣。实际上， 从几个方面来说，这几乎是有趣的。例如，这是26997 mod <n>某些值的图表n：

n   |  26997 % n
----+-----------
3   |  0
4   |  1
5   |  2
6   |  3
7   |  5 :(
8   |  5
9   |  6
10  |  7

但是，26997是可以用表示的少数几个数字之一，其中整数> 0。(n * 10)n - nn

这是可以用这种方式表示的前几个数字，此后我们将其称为加尔文数字：

9
398
26997
2559996
312499995
46655999994
8235429999993
1677721599999992
387420488999999991
99999999999999999990
28531167061099999999989
8916100448255999999999988
3028751065922529999999999987
1111200682555801599999999999986
437893890380859374999999999999985
184467440737095516159999999999999984
82724026188633676417699999999999999983
39346408075296537575423999999999999999982
19784196556603135891239789999999999999999981
10485759999999999999999999999999999999999999980

这些卡尔文数具有一些有趣的属性。当我们右对齐并突出显示所有9s 时，会出现更多模式：

我们对此挑战感兴趣的是：

• 无论如何n，每个加尔文数都以结尾 。10n - n

  所以，卡尔文（1）的端部9，卡尔文（2）与端98，而图案继续997，9996，99995等等，每一个连续的卡尔文数量递减计数并增加一个额外的9到开始处。

• 对于nwhere的值n % 10 == 0（n即被10整除），Calvin（n）以结尾。102n - n

  也就是说，该模式的扩展位数是正常数字的两倍，且9开头的s 数量等于n。

• 当n是的功率10（10，100，1000等），该图案进一步-每单位可以是一个延伸9或一个0。

  该模式如下： 9和 0。这在图表中更容易理解（无论如何，您的解决方案只需要处理最多10000个数字，这就是您所需要的）：(n + 1) * 10n - nn

  n      |  Calvin(n)
  -------+-----------------------
  10     |  19 nines, 1 zero
  100    |  298 nines, 2 zeroes
  1000   |  3997 nines, 3 zeroes
  10000  |  49998 nines, 4 zeroes
  

  九分的数字甚至表现出加尔文数字 本身的几个属性，但这对于这个挑战来说太过分了。

挑战

卡尔文数变得太大，太快，以至于“使第n个卡尔文数挑战在没有任意精度整数的语言中可行。因此，挑战在于确定数字是否适合上述模式，即是否适合一个数字是否为“候选加尔文数字”。

以下是将号码视为候选加尔文号码 （以下简称为CCN）的标准：

• 它以适合整数的模式结尾的数字 。10n - nn

  因此，要成为CCN，数字必须以9或98或997、9996、99995等结尾。

• 如果最后一位是0，则它也必须以结束，与 上一点相同。102n - nn

  这意味着它12312312399999999999999999999999999999999999980不是CCN，而是10485759999999999999999999999999999999999999980（实际上是正确的）。

• 如果n前两个步骤中的值是10的幂，则整数必须适合上述的第三种模式。

输入输出

输入将以字符串形式提供，并且将始终表示小于的数字Calvin(10000) + 10000（也可以表示为 ）。（为澄清起见，最大可能的输入是50000个9，最小可能的输入是。）10500001

如果输入表示一个数字，则输出应为真实值，否则为假值。有关这些术语的定义，请参见meta。

测试用例

应产生真实值的输入：

9
26997
99999999999999999990
437893890380859374999999999999985
10485759999999999999999999999999999999999999980
999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999900
259232147948794494594485446818048254863271026096382337884099237269509380022108148908589797968903058274437782549758243999867043174477180579595714249308002763427793979644775390624999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999850
1027092382693614216458468213549848274267264533712122209400214436472662418869004625362768700557725707157332451380426829473630485959339004149867738722096608953864534215649211386152032635755501464142277508289403434891444020975243742942368836579910208098242623061684967794815600266752580663281483595687307649904776800899000484103534573979334062832465904049046104660220505973505050538180250643437654409375728443182380726453925959886901573523090619465866810938078629561306599174923972607310649219442207992951278588892681161967770532314854195892941913447519131828356181219857012229150315613569162930098836696593474888020746503116685472977764615483225628639443918309216648893055765917642528801571387940219884056021782642758517893124803355573565644666880920219871370649806723296262307899148031362558110611562055614190049332906933360406981359187305353360484377948591528385990255894034369523166777375785900198782250651053530165824984161319460372145229568890321167955690544235365954748429659526071133879976348254667755220636244075595290123987745560038255541751251200827018722242010925729483977388235141539109139120069464709993781356334885359200734157439642935779132120725231008699003342908280056975158266782782304550273268246184659474285971272532354920744956064671379745219778013465792544241259691493098443741845166419905920702654683993902052727208789915748213660571390107102976665776293366616518962323688316843422737162297255648351087284877987537325761187239807598009767936409247247417410607537333841650998421607775989879490006136112078031237742552602618996017404602674987181629319060214150458746352191115606789019875790921190573561400752476956787515392210098071407806221412149732955903681690377998882038499470092453400748916257640501488510563314141992573250882286817352407459053866180642034662845694338400386823496563185664221362457851894843439705365082614359220653285052800751906334000698723288454227654466240011140570190301931122357632719033275258503935182047714841766010764632214069382579660602964184231995352310981811428980530707871661256260926759509418970021224649566130995825802676411575264295689037775857674060557127369881379685432291930869072749065675720647595081516460449973211035071920099349836074945813885239767788449030051892470053308048906746273036871919251738920141071153777908913021898541658119513188402271468288293408246833819954990709460114510017598873554406350044072275643892449218394225569069468466660333869360644718801813500285081977089623921689922204185138003164149106921903053243405307546841149889662566529697217181329051855403329741409045760789280950603184354320839342588593832348459938736210265795978675460906504449491132656307256451707333439200130425932724262464823848348296787445624028385464112471408499986690593095395244034885421580844176161027627954578726208600199909963055422192706751708210693468639072881081717288837393188012794669089175022406897622823484220002211676520484520241135615999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999028

输入应导致虚假的值：

1
26897
79999999999999999990
437893890380859374299999999999985
12312312399999999999999999999999999999999999980
999998999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999900
259232147948794494594485446818048254863271026096382337884099237269509380022108148908589797968903058274437782549758243999867043174477180579595714249308002763427793979644775390624999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999911111
1027092382693614216458468213549848274267264533712122209400214436472662418869004625362768700557725707157332451380426829473630485959339004149867738722096608953864534215649211386152032635755501464142277508289403434891444020975243742942368836579910208098242623061684967794815600266752580663281483595687307649904776800899000484103534573979334062832465904049046104660220505973505050538180250643437654409375728443182380726453925959886901573523090619465866810938078629561306599174923972607310649219442207992951278588892681161967770532314854195892941913447519131828356181219857012229150315613569162930098836696593474888020746503116685472977764615483225628639443918309216648893055765917642528801571387940219884056021782642758517893124803355573565644666880920219871370649806723296262307899148031362558110611562055614190049332906933360406981359187305353360484377948591528385990255894034369523166777375785900198782250651053530165824984161319460372145229568890321167955690544235365954748429659526071133879976348254667755220636244075595290123987745560038255541751251200827018722242010925729483977388235141539109139120069464709993781356334885359200734157439642935779132120725231008699003342908280056975158266782782304550273268246184659474285971272532354920744956064671379745219778013465792544241259691493098443741845166419905920702654683993902052727208789915748213660571390107102976665776293366616518962323688316843422737162297255648351087284877987537325761187239807598009767936409247247417410607537333841650998421607775989879490006136112078031237742552602618996017404602674987181629319060214150458746352191115606789019875790921190573561400752476956787515392210098071407806221412149732955903681690377998882038499470092453400748916257640501488510563314141992573250882286817352407459053866180642034662845694338400386823496563185664221362457851894843439705365082614359220653285052800751906334000698723288454227654466240011140570190301931122357632719033275258503935182047714841766010764632214069382579660602964184231995352310981811428980530707871661256260926759509418970021224649566130995825802676411575264295689037775857674060557127369881379685432291930869072749065675720647595081516460449973211035071920099349836074945813885239767788449030051892470053308048906746273036871919251738920141071153777908913021898541658119513188402271468288293408246833819954990709460114510017598873554406350044072275643892449218394225569069468466660333869360644718801813500285081977089623921689922204185138003164149106921903053243405307546841149889662566529697217181329051855403329741409045760789280950603184354320839342588593832348459938736210265795978675460906504449491132656307256451707333439200130425932724262464823848348296787445624028385464112471408499986690593095395244034885421580844176161027627954578726208600199909963055422192706751708210693468639072881081717288837393188012794669089175022406897622823484220002211676520484520241135615999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999027

规则

• 如果您的语言支持任意精度的整数（或数字类型具有足够高的精度以允许存储大于此的数字），则您可能无法在程序中的任何时候处理大于 18446744073709551615（）的整数。264

  这仅仅是为了防止解决方案遍历所有可能的Calvin数（或的所有可能的值）。10n - n

• 这是code-golf，因此以字节为单位的最短代码将获胜。

球拍353

(require srfi/13)(let([s(~a(read))])(for/or([n(range 1 999)])(and(let*([y(string-length(~a n))])(string-suffix?(string-append(make-string(-(if(=(modulo n 10)0)(* 2 n)n)y)#\9)(~r #:min-width y #:pad-string"0"(-(expt 10 y)n)))s))(let([n(inexact->exact(/(log n)(log 10)))])(or(not(integer? n))(string-prefix?(make-string(-(*(+ 1 n)(expt 10 n))n)#\9)s))))))

接受来自stdin，输出#t或的数字#f。

非高尔夫版本：

(require srfi/13)

(define (calvin? str)
  (for/or ([n (in-range 1 10001)])
    (and (10^n-n$? n str)
         (or (not (integer? (/ (log n) (log 10))))
             (expt-of-ten-check? n str)))))

(define (10^n-n$? n str)
  (let* ([div-by-ten? (zero? (modulo n 10))]
         [digits (string-length (~a n))]
         [nines (- (if div-by-ten? (* 2 n) n) digits)]
         [suffix (string-append (make-string nines #\9)
                                (~r #:min-width digits #:pad-string "0" (- (expt 10 digits) n)))])
    (string-suffix? suffix str)))

(define (expt-of-ten-check? n str)
  (let* ([n (inexact->exact (/ (log n) (log 10)))]
         [nines (- (* (add1 n) (expt 10 n)) n)]
         [prefix (make-string nines #\9)])
    (string-prefix? prefix str)))

我通常不打高尔夫球，Racket当然也不是最适合的语言，但是还没有人回答，所以我认为我会尝试一下。;）