Algorithms—136.Single Number

思路：异或计算。0^a=a;a^b=b^a。

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