Single Number

class Solution:
    # @param {integer[]} nums
    # @return {integer}
    def singleNumber(self, nums):
        ans = 0
        for num in nums:
            ans ^= num
        return ans

public class Solution {
    public int singleNumber(int[] A) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(A == null || A.length == 0){
            return 0;
        }
        int result = A[0];
        
        for(int i = 1; i < A.length; i++){
            result = result ^ A[i];
        }
        return result;
    }
}