20 lines
627 B
Racket
20 lines
627 B
Racket
#lang racket
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(define (best-shuffle s)
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(define len (string-length s))
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(define @ string-ref)
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(define r (list->string (shuffle (string->list s))))
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(for* ([i (in-range len)] [j (in-range len)])
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(when (not (or (= i j) (eq? (@ s i) (@ r j)) (eq? (@ s j) (@ r i))))
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(define t (@ r i))
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(string-set! r i (@ r j))
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(string-set! r j t)))
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r)
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(define (count-same s1 s2)
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(for/sum ([c1 (in-string s1)] [c2 (in-string s2)])
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(if (eq? c1 c2) 1 0)))
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(for ([s (in-list '("abracadabra" "seesaw" "elk" "grrrrrr" "up" "a"))])
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(define sh (best-shuffle s))
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(printf " ~a, ~a, (~a)\n" s sh (count-same s sh)))
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