leetcode 268. Missing Number

用异或解决

用https://www.cnblogs.com/grandyang/p/4756677.html的第二种方法

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

 https://blog.csdn.net/ebowtang/article/details/50457902