不使用额外空间的情况下实现两数交换

基本原理：数字a与数字a异或结果为0，即抵消掉！

基于此，首先让 a = a ^ b，然后 b = a ^ b = (a ^ b) ^ b = a，最后，a = a ^ b = (a ^ b) ^ a = b（注意原来的b对应现在的a了）。

package com.ly.test;


public class MyTest {
    public static void main(String[] args) {
        int a = -2020;
        int b = 2020;
        System.out.println("交换前：" + "[a = " + a + "," + " b = " + b + "]");

        a = a ^ b;
        b = a ^ b;
        a = a ^ b;
        System.out.println("交换后：" + "[a = " + a + "," + " b = " + b + "]");
    }
}

交换前：[a = -2020, b = 2020]
交换后：[a = 2020, b = -2020]

Process finished with exit code 0