219.contains-duplicate-ii.js

/*
 * @lc app=leetcode id=219 lang=javascript
 *
 * [219] Contains Duplicate II
 *
 * https://leetcode.com/problems/contains-duplicate-ii/description/
 *
 * algorithms
 * Easy (34.15%)
 * Total Accepted:    173.6K
 * Total Submissions: 508.3K
 * Testcase Example:  '[1,2,3,1]\n3'
 *
 * 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
 *
 *
 *
 *
 *
 */
/**
 * @param {number[]} nums
 * @param {number} k
 * @return {boolean}
 */
var containsNearbyDuplicate = function(nums, k) {
  const lastIndex = new Map();
  return nums.some((n, i) => {
    if (lastIndex.has(n) && i - lastIndex.get(n) <= k)
      return true;
    lastIndex.set(n, i);
    return false;
  })
};