LeetCode(268) Missing Number

[code]class Solution {
public:
    int missingNumber(vector<int>& nums) {
        //math solution by sum total
        int sum = nums.size() * (nums.size() + 1) / 2;
        for(int i = 0; i < nums.size(); i++)
            sum -= nums[i];

        return sum;

    }
};