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Contains Duplicate II

Problem statement​

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 = 3Output: true

Example 2:

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

Example 3:

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

Constraints:

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

My solution​

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {boolean}
 */
var containsNearbyDuplicate = function(nums, k) {
    const track = {};
    
    for(let i = 0; i < nums.length; i++) {
        if (track[nums[i]] === undefined || Math.abs(track[nums[i]] - i) > k) {
            track[nums[i]] = i;
        } else if(Math.abs(track[nums[i]] - i) <= k) {
            return true;
        }
    }
    return false;
};