LeetCode Problem Number: 268

Missing Number

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

Example 2:

Input: nums = [0,1]
Output: 2

Example 3:

Input: nums = [9,6,4,2,3,5,7,0,1]
Output: 8

Solution Code

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

Solution Explanation

The problem requires finding the missing number in an array of distinct numbers ranging from 0 to n. The solution uses the sum formula as follows:

• Sum Formula: The sum of the first n natural numbers is given by the formula n * (n + 1) / 2.
• Array Sum: Calculate the sum of the elements in the array.
• Missing Number: Subtract the sum of the array from the total sum to get the missing number.