219. 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.

Constraints

Approach

Links

• GeeksforGeeks

• Leetcode

• ProgramCreek

• YouTube

Examples

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

Solutions

Solution 1

/**
 * Time complexity : O(N*min(N, K))
 * Space complexity : O(1)
 */

class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        for(int i = 0; i < nums.length; i++) {
            for(int j = Math.max(i - k, 0); j < i; j++) {
                if(nums[i] == nums[j]) {
                    return true;
                }
            }
        }
        return false;
    }
}

Solution 2

/**
 * Time complexity : O(N)
 * Space complexity : O(min(N, K))
 */
 
 class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        Set<Integer> set = new HashSet();
        for(int i = 0; i < nums.length; i++) {
            if(!set.add(nums[i])) return true;
            if(set.size() > k) {
                set.remove(nums[i-k]);
            }
        }
        return false;
    }
}

Follow up