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Ingy döt Net 2015-02-20 09:02:09 -05:00
parent 00a190b0a6
commit 91df62d461
5697 changed files with 93386 additions and 804 deletions
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11
Task/Quickselect-algorithm/Racket/quickselect-algorithm.rkt Normal file
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(define (quickselect A k)
(define pivot (list-ref A (random (length A))))
(define A1 (filter (curry > pivot) A))
(define A2 (filter (curry < pivot) A))
(cond
[(<= k (length A1)) (quickselect A1 k)]
[(> k (- (length A) (length A2))) (quickselect A2 (- k (- (length A) (length A2))))]
[else pivot]))
(define a '(9 8 7 6 5 0 1 2 3 4))
(display (string-join (map number->string (for/list ([k 10]) (quickselect a (+ 1 k)))) ", "))