# [268\. Missing Number](https://leetcode.com/problems/missing-number/) :::spoiler Solution Sort ```cpp= class Solution { public: int missingNumber(vector<int>& nums) { int n = nums.size(); for(int i = 0; i < nums.size(); i++) { n += i - nums[i]; } return n; } }; ``` - T: $O(n)$ - S: $O(1)$ :::