Skip to content

219 Contains Duplicate II

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

Solution:

class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        Set<Integer> set = new HashSet<>();
        for (int i = 0; i < nums.length; i++){
            if (set.contains(nums[i])){
                return true;
            }
            set.add(nums[i]);
            if (set.size() > k){
                set.remove(nums[i-k]);
            }
        }
        return false;
    }
}
// TC:O(n)
// SC:O(min(n, k))