Given an array of integers, every element appears twice except for one. Find that single one.
Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
给定一个数组，数组中除了一个数只出现了一次，其他数都出现了两次，找出那个数。
把所有的数字进行异或运算即可。
class Solution {
public int singleNumber(int[] nums) {
int n = 0;
for (int num : nums) {
n ^= num;
}
return n;
}
}