[LeetCode] Single Number

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

查了题解, 真特么巧妙.

在一堆成双入对的情侣中间 寻找一个无人陪伴的屌丝.
方法是 把情侣全干死, 剩下的屌丝 昭然若揭.
武器是: 异或

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