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Ingy döt Net 2013-04-10 23:57:08 -07:00
parent 47bf37c096
commit b83f433714
12433 changed files with 156208 additions and 123 deletions
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15
Task/Run-length-encoding/Scheme/run-length-encoding.ss Normal file
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(define (run-length-decode v)
(apply string-append (map (lambda (p) (make-string (car p) (cdr p))) v)))
(define (run-length-encode s)
(let ((n (string-length s)))
(let loop ((i (- n 2)) (c (string-ref s (- n 1))) (k 1) (v '()))
(if (negative? i) (cons (cons k c) v)
(let ((x (string-ref s i)))
(if (char=? c x) (loop (- i 1) c (+ k 1) v)
(loop (- i 1) x 1 (cons (cons k c) v))))))))
(run-length-encode "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW")
; ((12 . #\W) (1 . #\B) (12 . #\W) (3 . #\B) (24 . #\W) (1 . #\B) (14 . #\W))
(run-length-decode '((12 . #\W) (1 . #\B) (12 . #\W) (3 . #\B) (24 . #\W) (1 . #\B) (14 . #\W)))
; "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW"