34 lines
791 B
Scheme
34 lines
791 B
Scheme
#lang sicp
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(define (make-point x y)
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(cons x y))
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(define (x-point p)
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(car p))
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(define (y-point p)
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(cdr p))
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; top-left point, bottom-right point representation
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(define (tlbr-rect a b)
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(cons 'tlbr (cons a b)))
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; center point, width, height representation
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(define (cpwh-rect p w h)
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(cons 'cpwh
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(cons p
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(cons w h))))
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(define (height rect)
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(cond ((eq? 'cpwh (car rect)) (cdddr rect))
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(else (abs (- (y-point (cadr rect))
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(y-point (cddr rect)))))))
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(define (width rect)
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(cond ((eq? 'cpwh (car rect)) (caddr rect))
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(else (abs (- (x-point (cadr rect))
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(x-point (cddr rect)))))))
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(define (perimeter rect)
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(* 2 (+ (width rect) (height rect))))
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(define (area rect)
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(* (width rect) (height rect)))
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