Swap Without Extra Variable

Given two variables, x and y, swap two variables without using a third variable.

Example

Given x = 10, y = 5
Return 15.

思路：考察位运算，异或。 同一个数异或两次还是其本身。

 1 class Solution {
 2 public:
 3     /**
 4      * @param x an integer
 5      * @param y an integer
 6      * @return nothing
 7      */
 8     void swap(int &x, int &y) {
 9         // Write your code here
10         x = x ^ y;
11         y = x ^ y;
12         x = x ^ y;
13     }
14 };