LeetCode 219 Contains Duplicate II | HashMap Solution Explained Simply

In this video, we solve LeetCode 219: Contains Duplicate II using a simple HashMap approach. The problem asks us to check whether the same number appears again within a distance of at most k. We will understand: What the problem is asking Why checking only duplicates is not enough How index distance works How to use a HashMap to store the last seen index Why the solution runs in O(n) time This problem is a great introduction to using HashMaps for index-based problems. Code idea: Store the last index of every number. If the same number appears again and the distance is less than or equal to k, return true. Time Complexity: O(n) Space Complexity: O(n) #leetcode #dsa #python #hashmap #codinginterview