Question

有人能弄清楚此递归代码如何工作以及为什么输出它的作用吗？
也许您可以包括实现其输出所要经过的步骤？非常感谢！附加了代码...（它输出bdefh）。
另请注意，我是初学者。

public class difficult {

    public static void main(String[] args) {
        mysteryMix("abcdefgh!");
    }

    public static void mysteryMix(String str) {
        System.out.println("i entered loop");
        System.out.println(str);
        int length=str.length();
        if(length>=3)
        {
            System.out.println(str);
            System.out.println("I entered if statement");
            mysteryMix(str.substring(0,length/3));
            System.out.println(str);
            System.out.println("FOR REAL PRINT: " +str.substring(length/3,2*length/3));
            System.out.println("length "+length);
            System.out.println(length/3);
            System.out.println(2*length/3);
            mysteryMix(str.substring(2*length/3));
        }   
    }
}

Answer 1

Relevant statement                                      Output
=================================================       ======================
mysteryMix("abcdefgh!")
  System.out.println("i entered loop");                 i entered loop
  System.out.println(str);                              abcdefgh!
  System.out.println(str);                              abcdefgh!
  System.out.println("I entered if statement");         I entered if statement
  mysteryMix("abc")
    System.out.println("i entered loop");               i entered loop
    System.out.println(str);                            abc
    System.out.println(str);                            abc
    System.out.println("I entered if statement");       I entered if statement
    mysteryMix("a")
      System.out.println("i entered loop");             i entered loop
      System.out.println(str);                          a
    System.out.println(str);                            abc
    System.out.println(...);                            FOR REAL PRINT: b
    System.out.println("length "+length);               length 3
    System.out.println(length/3);                       1
    System.out.println(2*length/3);                     2
    mysteryMix("c")
      System.out.println("i entered loop");             i entered loop
      System.out.println(str);                          c
  System.out.println(str);                              abcdefgh!
  System.out.println(...);                              FOR REAL PRINT: def
  System.out.println("length "+length);                 length 9
  System.out.println(length/3);                         3
  System.out.println(2*length/3);                       6
  mysteryMix("gh!")
    . . . and so forth

递归输出不符合预期

1 个答案: