SICP 2.3 习题答案

最新推荐文章于 2019-01-17 14:04:40 发布

原创最新推荐文章于 2019-01-17 14:04:40 发布 · 132 阅读

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本文通过Scheme语言定义了一系列过程来创建点和矩形，并实现对矩形的几何属性如宽度、高度、周长及面积的计算。

可能书上想让我用2.2的答案，实在不想那么搞。。。

(define (make-point x y) (cons x y))
(define (x-point p) (car p))
(define (y-point p) (cdr p))

(define (make-rect left-top right-bottom) (cons left-top right-bottom))
(define (bottom-left rect)
  (make-point (x-point (car rect))
              (y-point (cdr rect))))
(define (bottom-right rect) (cdr rect))
(define (top-left rect) (car rect))
(define (top-right rect)
  (make-point (x-point (cdr rect))
              (y-point (car rect))))
(define (width-rect rect)
  (abs (- (x-point (car rect)) (x-point (cdr rect)))))
(define (height-rect rect)
  (abs (- (y-point (car rect)) (y-point (cdr rect)))))
(define (perimeter-rect rect)
  (* 2 (+ (width-rect rect) (height-rect rect))))
(define (area-rect rect)
  (* (width-rect rect) (height-rect rect)))