如何工作递归并绘制递归树 [英] How work recursion and draw recursion tree

问题描述

 public static void allCombination(char[] S, int start, int r, String output) {
        int length = S.length;
        if (r == 1) {
            for (int i = start; i < length; i++) {

                System.out.println(output + S[i]);
            }
        } else {
            for (int k = start; k < length - r + 1; k++) {

                allCombination(S, k + 1, r - 1, output + S[k]);
            }
        }

嘿，运行上面的代码可以组合给定的字符串(我从互联网上拿来的).你能告诉我这个递归是如何工作的以及我如何为此绘制递归树(我是编程新手).

Hey tied to run above code to make possible combination of a given String(I took it from internet).Can you tell me how this recursion work and how i draw recursion tree for that(I am new to programming).

推荐答案

只需从纸的顶部开始，为第一个调用绘制一个框.然后跟踪代码，寻找任何对自身的调用，在第一个调用下为新调用绘制一个框.然后遍历第二层的每个框并重复该过程.

Just start at the top of the paper, draw a box for the first call. Then trace through the code looking for any call back to itself, draw a box for the new call(s) under the first one. Then go through each of the boxes at the second level and repeat the process.

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