Problem 8 » 履歴 » リビジョン 2
リビジョン 1 (Noppi, 2023/12/27 01:48) → リビジョン 2/8 (Noppi, 2023/12/27 01:51)
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# [[Problem 8]]
```scheme
#!r6rs
#!chezscheme
(import (chezscheme))
(define Problem8-number-string
(string-append "73167176531330624919225119674426574742355349194934"
"96983520312774506326239578318016984801869478851843"
"85861560789112949495459501737958331952853208805511"
"12540698747158523863050715693290963295227443043557"
"66896648950445244523161731856403098711121722383113"
"62229893423380308135336276614282806444486645238749"
"30358907296290491560440772390713810515859307960866"
"70172427121883998797908792274921901699720888093776"
"65727333001053367881220235421809751254540594752243"
"52584907711670556013604839586446706324415722155397"
"53697817977846174064955149290862569321978468622482"
"83972241375657056057490261407972968652414535100474"
"82166370484403199890008895243450658541227588666881"
"16427171479924442928230863465674813919123162824586"
"17866458359124566529476545682848912883142607690042"
"24219022671055626321111109370544217506941658960408"
"07198403850962455444362981230987879927244284909188"
"84580156166097919133875499200524063689912560717606"
"05886116467109405077541002256983155200055935729725"
"71636269561882670428252483600823257530420752963450"))
(define answer-8
(let ((count (- (string-length Problem8-number-string) p8-num-string) 13)))
(let loop ((index 0) (max-num 0))
(if (< count index)
max-num
(let* ((sub-num (substring Problem8-number-string index (+ index 13)))
(char-lis (string->list sub-num))
(num-lis (map
(lambda (char)
(- (char->integer char)
(char->integer #\0)))
char-lis))
(product-num (fold-left * 1 num-lis)))
(loop (add1 index) (max max-num product-num)))))))
(printf "8: ~D~%" answer-8)
```