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:

class Solution {
public boolean containsNearbyDuplicate(int[] nums, int k) {
Map<Integer, List<Integer>> map = new HashMap<>();
for (int i = 0; i<nums.length; i++) {
List<Integer> indices = map.getOrDefault(nums[i], new ArrayList<>());
for (int j : indices) {
if (Math.abs(i - j) <= k) {
return true;
}
}
indices.add(i);
map.put(nums[i], indices);
}
return false;
}
}

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