Leetcode-Single Number

Given an array of integers, every element appears twice except for one. Find that single one.

Analysis:

Use XOR operation.

Solution:

public class Solution {
    public int singleNumber(int[] A) {
        if (A.length==0) return -1;
        int res = A[0];
        for (int i=1;i<A.length;i++)
            res = res^A[i];
        return res;
        
    }
}