0268. Missing Number.md

Array

T.C. O(n)

/**
 * @param {number[]} nums
 * @return {number}
 */
var missingNumber = function(nums) {
    let res = new Array(nums.length + 1).fill(-1);

    for(let num of nums) {
        res[num] = num;
    }

    return res.indexOf(-1);
};