Arthur Barraux
48 lines
1.7 KiB
Scheme
48 lines
1.7 KiB
Scheme
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(define large-num (string-append
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"73167176531330624919225119674426574742355349194934"
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"96983520312774506326239578318016984801869478851843"
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"85861560789112949495459501737958331952853208805511"
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"12540698747158523863050715693290963295227443043557"
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"66896648950445244523161731856403098711121722383113"
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"62229893423380308135336276614282806444486645238749"
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"30358907296290491560440772390713810515859307960866"
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"70172427121883998797908792274921901699720888093776"
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"65727333001053367881220235421809751254540594752243"
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"52584907711670556013604839586446706324415722155397"
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"53697817977846174064955149290862569321978468622482"
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"83972241375657056057490261407972968652414535100474"
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"82166370484403199890008895243450658541227588666881"
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"16427171479924442928230863465674813919123162824586"
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"17866458359124566529476545682848912883142607690042"
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"24219022671055626321111109370544217506941658960408"
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"07198403850962455444362981230987879927244284909188"
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"84580156166097919133875499200524063689912560717606"
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"05886116467109405077541002256983155200055935729725"
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"71636269561882670428252483600823257530420752963450"))
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(define width 13)
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(define (char->number c)
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(if (char-numeric? c)
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(- (char->integer c) (char->integer #\0))
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-1))
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(define (substring->numbers subs)
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(map char->number (string->list subs)))
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(define (iter i largest)
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(if (>= (+ i width) (string-length large-num))
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largest
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(let* ((sub (substring large-num i (+ i width)))
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(set (substring->numbers sub))
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(product (apply * set)))
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(if (> product (car largest))
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(iter (+ i 1) (cons product set))
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(iter (+ i 1) largest)))))
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(display (iter 0 '(-1 . '())))
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