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43 lines
887 B
Racket
43 lines
887 B
Racket
(define (multiply a b)
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(define (iter a b product)
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(if (= b 0)
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product
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(iter a (- b 1) (+ product a))))
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(iter a b 0))
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; multiply
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(define (sqr n)
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(multiply n n))
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(define (divide a b)
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(define (iter a b product)
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(cond ((= a 0) product)
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((< a 0) (- product 1))
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(else (iter (- a b) b (+ product 1)))))
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(iter a b 0))
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; divide
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(define (halve a)
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(divide a 2))
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(define (fast-ext number power)
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(define (iter number power product)
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(cond ((= power 0) product)
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((even? power) (iter (sqr number)
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(halve power)
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product))
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(else (iter number
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(- power 1)
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(multiply number product)))))
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(iter number power 1))
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; fast-ext
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(fast-ext 5 3)
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(fast-ext 2 2)
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(fast-ext 1 2)
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(fast-ext 9 4)
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(fast-ext 2 0)
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(fast-ext 7 1) |