leetcode---Missing Number---位

Given an array containing n distinct numbers taken from 0, 1, 2, …, n, find the one that is missing from the array.

For example,
Given nums = [0, 1, 3] return 2.

Note:
Your algorithm should run in linear runtime complexity. Could you implement it using only constant extra space complexity?

class Solution {public:    int missingNumber(vector<int>& nums)     {        int n = nums.size();        int result = 0;        for(int i=0; i<n; i++)        {            result ^= (i+1) ^ nums[i];        }        return result;    }};