some solutions for MIT Press's "structure and interpretation of computer programs", I guess
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(define (double x) |
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(+ x x)) |
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(define (halve x) |
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(/ x 2)) |
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(define (nice-mult a b) |
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(define (iter acc a b) |
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(cond ((zero? b) acc) |
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((even? b) (iter acc (double a) (halve b))) |
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(else (iter (+ acc a) (double a) (halve (- b 1)))))) |
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(iter 0 a b))
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