268. Missing Number，268missingnumber

268. Missing Number，268missingnumber

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?

 1 class Solution {
 2 public:
 3     int missingNumber(vector<int>& nums) {
 4         int number = 0;
 5         for(int i = 0; i <= nums.size(); i++)
 6             number ^= i;
 7         for(auto n : nums)
 8             number ^= n;
 9             
10         return number;
11     }
12 };