Problem Statement Clone Graph LeetCode Solution – We are given a reference of a node in a connected undirected graph and are asked to return a deep copy of the graph. A deep copy is basically a clone where no node present in the deep copy should have the reference …
Problem Statement The Valid Parentheses LeetCode Solution – “Valid Parentheses” states that you’re given a string containing just the characters ‘(‘, ‘)’, ‘{‘, ‘}’, ‘[‘ and ‘]’. We need to determine whether the input string is a valid string or not. A string is said to be a valid string if open brackets must be closed …
Problem Statement First Unique Character in a String LeetCode Solution – Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1. Example Test Case 1: Input: s = “leetcode” Output: 0 Test Case 2: Input: s = “aabb” Output: -1 Explanation …
Problem Statement: Invert Binary Tree LeetCode Solution – In this question, Given a root of any binary tree, the solution is required to invert the binary tree meaning the left tree should become the right tree and vice versa. Explanation We can ask ourselves which tree traversal would be …
Problem Statement Design Browser History LeetCode Solution – You have a browser with one tab where you start on the homepage and you can visit another url, get back in the history number of steps or move forward in the history number of steps. Implement the BrowserHistory class: BrowserHistory(string homepage) Initializes the object with the homepage of the …
Problem Statement Evaluate Reverse Polish Notation LeetCode Solution – Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are +, -, *, and /. Each operand may be an integer or another expression. Note that the division between two integers should truncate toward zero. It is guaranteed that the given …
Problem Statement 3Sum Closest LeetCode Solution – Given an integer array nums of length n and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input would have exactly one solution. Input: nums = [-1,2,1,-4], target = 1 Output: …
Problem Statement Binary Tree Right Side View LeetCode Solution – Given the root of a binary tree, imagine yourself standing on the right side of it, and return the values of the nodes you can see ordered from top to bottom. Example Test Case 1: Input: root = [1, 2, 3, null, 5, null, …
Problem Statement Time Based Key-Value Store LeetCode Solution – Design a time-based key-value data structure that can store multiple values for the same key at different time stamps and retrieve the key’s value at a certain timestamp. Implement the TimeMap class: TimeMap() Initializes the object of the data structure. void set(String key, String …
Problem Statement Find Median from Data Stream LeetCode Solution – The median is the middle value in an ordered integer list. If the size of the list is even, there is no middle value and the median is the mean of the two middle values. For example, for arr = [2,3,4], the median …