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  1. ; frequency counts
  2.  
  3. (define (freq vec)
  4.   (let ((n (vector-length vec)))
  5.     (let loop ((i 0))
  6.       (cond ((= i n) (do ((j 0 (+ j 1))) ((= j n))
  7.                        (when (negative? (vector-ref vec j))
  8.                          (display (+ j 1)) (display " ")
  9.                          (display (- (vector-ref vec j))) (newline))))
  10.             ((not (positive? (vector-ref vec i))) (loop (+ i 1)))
  11.             (else (let ((idx (- (vector-ref vec i) 1)))
  12.                     (cond ((positive? (vector-ref vec idx))
  13.                             (vector-set! vec i (vector-ref vec idx))
  14.                             (vector-set! vec idx -1)
  15.                             (loop i))
  16.                           (else (vector-set! vec idx
  17.                                   (- (vector-ref vec idx) 1))
  18.                                 (vector-set! vec i 0)
  19.                                 (loop (+ i 1))))))))))
  20.  
  21. (freq '#(2 3 3 2 5))
  22.  
  23. (define (freq vec)
  24.   (let ((n (vector-length vec)))
  25.     (do ((i 0 (+ i 1))) ((= i n))
  26.       (vector-set! vec i
  27.         (- (vector-ref vec i) 1)))
  28.     (do ((i 0 (+ i 1))) ((= i n))
  29.       (vector-set! vec (modulo (vector-ref vec i) n)
  30.         (+ (vector-ref vec (modulo (vector-ref vec i) n)) n)))
  31.     (do ((i 0 (+ i 1))) ((= i n))
  32.       (when (< n (vector-ref vec i))
  33.         (display (+ i 1)) (display " ")
  34.         (display (quotient (vector-ref vec i) n)) (newline)))
  35.     (do ((i 0 (+ i 1))) ((= i n))
  36.       (vector-set! vec i
  37.         (+ (remainder (vector-ref vec i) n) 1)))
  38.     (display vec) (newline))) ; show that vec is unchanged
  39.  
  40. (freq '#(2 3 3 2 5))
Success #stdin #stdout 0.01s 50224KB
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2 2
3 2
5 1
2 2
3 2
5 1
#(2 3 3 2 5)
https://ideone.com/nm6KzX
language:
Scheme (guile 2.2.4)
created:
5 years ago
visibility:
public

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