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  1. ; peaks
  2.  
  3. (define (subvector vec start end)
  4.   (let ((subvec (make-vector (- end start))))
  5.     (do ((i start (+ i 1)) (j 0 (+ j 1)))
  6.         ((= i end) subvec)
  7.       (vector-set! subvec j (vector-ref vec i)))))
  8.  
  9. (define (peaks vec)
  10.   (let ((len (vector-length vec)))
  11.     (let loop ((first 0) (last 1) (subvecs (list)))
  12.       (cond ((= last len) (reverse subvecs))
  13.             ((and (< (vector-ref vec first)
  14.                      (vector-ref vec last))
  15.                   (= (vector-ref vec last)
  16.                      (vector-ref vec (+ last 1))))
  17.               (loop first (+ last 1) subvecs))
  18.             ((and (< (vector-ref vec first)
  19.                      (vector-ref vec last))
  20.                   (> (vector-ref vec last)
  21.                      (vector-ref vec (+ last 1))))
  22.               (loop (+ last 1) (+ last 2)
  23.                     (cons (subvector vec first (+ last 2)) subvecs)))
  24.             (else (loop last (+ last 1) subvecs))))))
  25.  
  26. (display (peaks (vector 5 5 4 5 4))) (newline)
  27. (display (peaks (vector 6 5 4 4 4 4 4 5 6 7 7 7 7 7 6))) (newline)
  28. (display (peaks (vector 5 5 5 5 4 5 4 5 6 7 8 8 8 8 8 9 9 8))) (newline)
Success #stdin #stdout 0.01s 50288KB
comments (?)
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Standard input is empty
stdout
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(#(4 5 4))
(#(6 7 7 7 7 7 6))
(#(4 5 4) #(8 9 9 8))
https://ideone.com/Vp0vFc
language:
Scheme (guile 2.2.4)
created:
5 years ago
visibility:
public

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