Leetcode 268 Missing Number

Leetcode 268 Missing Number

#include <vector>#include <algorithm>using namespace std;class Solution {public:    int missingNumber(vector<int>& nums) {        if (nums.size() == 1 && nums[0] == 0)            return 1;        sort(nums.begin(), nums.end());        for (int i = 0; i < nums.size(); i++){            if (nums[i] != i)                return i;        }        return nums[nums.size()-1] + 1;    }};//等差数列求和(a1+an)n/2，因为只少一个值，所以可以减出来class Solution {public:    int missingNumber(vector<int>& nums) {        int size = nums.size();        int sum = (size + 1) * size / 2;        for (int i = 0; i < size; i++)        {            sum -= nums[i];        }        return sum;    }};