Contains Duplicate II

Description

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most 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

Solution(javascript)

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