斐波那契计划 [英] Fibonacci in Scheme

问题描述

我试图理解Scheme中的递归，因此很难进行空运行，例如一个简单的斐波那契数问题.

I am trying to understand recursion in Scheme and I have a hard time doing the dry run for it, for example a simple Fibonacci number problem.

有人可以替我分解添加步骤吗?

Could someone break down the steps in which the additions take place, for me?

(define (fib n)
  (if (<= n 2)
      1
      (+ (fib (- n 1)) (fib (- n 2)))))

推荐答案

如果您使用的是Racket(如标签所示)，则说明您有内置的步进器.

If you're using Racket, as your tags indicate, then you have a built-in stepper.

将程序输入DrRacket，然后单击右上角菜单中的步骤":

Enter the program into DrRacket, and click Step in the top-right menu:

然后将打开一个步进器窗口.单击一遍又一遍"，您可以逐步完成程序的执行.

Then a stepper window will open up. Click Step over and over, and you can walk through the execution of the program.

如果您希望步数更易于管理，请选择一个小于10的数字以跟踪执行.

If you want the number of steps to be a bit more manageable, pick a number lower than 10 for the execution to trace.

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