missingNumber.js

////////////////////////////////////////////////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
// 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.
// Example 4:
// Input: nums = [0]
// Output: 1
// Explanation: n = 1 since there is 1 number, so all numbers are in the range [0,1]. 1 is the missing number in the range since it does not appear in nums.
/**
 * @param {number[]} nums
 * @return {number}
 */
 const missingNumber = function(nums) {
    let sum = 0, total = 0;
    for(let i = 0; i < nums.length; i++) {
        sum += nums[i];
        total += i + 1;
    }
    return total - sum;
};

// console.log(missingNumber([3,0,1]));
// console.log(missingNumber([0,1]));
// console.log(missingNumber([9,6,4,2,3,5,7,0,1]));
// console.log(missingNumber([0]));