0051_P268_Missing_Number.cpp

/* 
Day: 51
Problem Number: 268 (https://leetcode.com/problems/missing-number)
Date: 20-02-2024 
Description:
Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.
 
Example 1:
Input: nums = [3,0,1]
Output: 2
Explanation: n = 3 since there are 3 numbers, so all numbers are in the range [0,3]. 2 is the missing number in the range since it does not appear in nums.

Example 2:
Input: nums = [0,1]
Output: 2
Explanation: n = 2 since there are 2 numbers, so all numbers are in the range [0,2]. 2 is the missing number in the range since it does not appear in nums.

Example 3:
Input: nums = [9,6,4,2,3,5,7,0,1]
Output: 8
Explanation: n = 9 since there are 9 numbers, so all numbers are in the range [0,9]. 8 is the missing number in the range since it does not appear in nums.
 
Constraints:
* n == nums.length
* 1 <= n <= 10^4
* 0 <= nums[i] <= n
* All the numbers of nums are unique.

Code:  */
class Solution {
public:
    int missingNumber(vector<int>& nums) {
        int n = nums.size();
        return (1 + n) * n / 2 - accumulate(nums.begin(), nums.end(), 0);
    }
};