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) {
        Map<Integer, Integer> map = new HashMap<>();

        for (int i = 0; i < nums.length; i++){
            int cur = nums[i];
            if (map.containsKey(cur)){
                int index = map.get(cur);
                int abs = Math.abs(index - i);
                if (abs <= k){
                    return true;
                }
            }
            map.put(cur, i);
        }

        return false;


    }
}

// TC: O(n)
// SC: O(n)

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))