think2times

摘要： Exercise2.51 Define the below operation for painters. below takes two painters as arguments. The resulting painter, given a frame, draws with the firs 阅读全文

摘要： Exercise 2.50 Define the transformation flip-horiz, which flips painters horizontally, and transformations that rotate painters counterclockwise by 18 阅读全文

摘要： Exercise 2.49 Use segments->painter to define the following primitive painters: a. The painter that draws the outline of the designated frame. b. The 阅读全文

摘要： Exercise 2.48 A directed line segment in the plane can be represented as a pair of vectors—the vector running from the origin to the start-point of th 阅读全文

摘要： Exercise 2.47 Here are two possible constructors for frames: (define (make-frame origin edge1 edge2) (list origin edge1 edge2)) (define (make-frame or 阅读全文

摘要： Exercise 2.46 A two-dimensional vector v running from the origin to a point can be represented as a pair consisting of an x-coordinate and a y-coordin 阅读全文

摘要： right-split and up-split can be expressed as instances of a general splitting operation. Define a procedure split with the property that evaluating (d 阅读全文

摘要： 我在这一章遇到了一个大问题，就是书上用的那些函数 beside, wave, flip-vert 我统统用不了。我用的是 DrRacket 这个软件，在网上查了半天，终于找到了解决办法。 首先是官方教程，在 DrRacket 中依次打开 File -> Package Manager...，在弹出的 阅读全文

摘要： Exercise 2.43 Louis Reasoner is having a terrible time doing Exercise 2.42. His queens procedure seems to work, but it runs extremely slowly. (Louis n 阅读全文

摘要： 这道题太难了，我自己只完成了 empty-board 这一个定义，其他的函数即使看了别人的答案也研究了半天才搞明白。。 ; board-size 指的是正方形棋盘的长 (define (queens board-size) (define (queen-cols k) (if (= k 0) (li 阅读全文