20 lines
551 B
Racket
20 lines
551 B
Racket
#lang racket
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(define (Leonardo n #:L0 (L0 1) #:L1 (L1 1) #:1+ (1+ 1))
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(cond [(= n 0) L0]
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[(= n 1) L1]
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[else
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(let inr ((n (- n 2)) (L_n-2 L0) (L_n-1 L1))
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(let ((L_n (+ L_n-1 L_n-2 1+)))
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(if (zero? n) L_n (inr (sub1 n) L_n-1 L_n))))]))
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(module+ main
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(map Leonardo (range 25))
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(map (curry Leonardo #:L0 0 #:L1 1 #:1+ 0) (range 25)))
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(module+ test
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(require rackunit)
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(check-equal? (Leonardo 0) 1)
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(check-equal? (Leonardo 1) 1)
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(check-equal? (Leonardo 2) 3)
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(check-equal? (Leonardo 3) 5))
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