LeetCode 16 Single Number

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?

分析：位运算。

这个比Single Number要简单一点，只要将当前结果与遇到的数按位求异或（按位求异或，则该位出现两个1或者两个0得到的结果都是0，这样可以将出现两次的数清0，则剩下的必然是只出现了一次的那个数）。

public class Solution {
    public int singleNumber(int[] A) {
        int result = 0;
        for(int i=0; i<A.length; i++){
            result = result ^ A[i];
        }
        return result;
    }
}