Single Number

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

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?

解法: 可以根据异或运算的配对性定理可以解此题.配对性定理可以详见:http://wenku.baidu.com/view/8bb52ffb700abb68a982fbba.html

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