Contains Duplicate II - LeetCode javascript solutions

Problem

Given an integer array nums and an integer k, return true **if there are two *distinct indices* i and j in the array such that nums[i] == nums[j] and **abs(i - j) <= k.

Example 1:

Input: nums = [1,2,3,1], k = 3
Output: true

Example 2:

Input: nums = [1,0,1,1], k = 1
Output: true

Example 3:

Input: nums = [1,2,3,1,2,3], k = 2
Output: false

Constraints:

1 <= nums.length <= 105
-109 <= nums[i] <= 109
0 <= k <= 105

Solution

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {boolean}
 */
var containsNearbyDuplicate = function(nums, k) {
    var map = {};
    for (var i = 0; i < nums.length; i++) {
        if (map[nums[i]] !== undefined && i - map[nums[i]] <= k) return true;
        map[nums[i]] = i;
    }
    return false;
};

Explain:

nope.

Complexity:

Time complexity : O(n).
Space complexity : O(n).