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

Example 1:

Input: [3,0,1]
Output: 2

Example 2:

Input: [9,6,4,2,3,5,7,0,1]
Output: 8

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

解析：

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

• 268. Missing Number： https://leetcode.com/problems/missing-number/solution/