Leetcode-single Number

http://oj.leetcode.com/problems/single-number/

题目描述

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?

代码

    class Solution {
            public:
                int singleNumber(int A[], int n) {
                // IMPORTANT: Please reset any member data you declared, as
                // the same Solution instance will be reused for each test case.
                if(A == NULL || n == 0)
                    return 0;
                int result = A[0];
                for(int i = 1; i < n; i++)
                    result = result ^ A[i];
                return result;
                }
            };