Problem Statement Construct Binary Tree from Preorder and Postorder Traversal LeetCode Solution – Given two integer arrays, preorder and postorder where preorder is the preorder traversal of a binary tree of distinct values and postorder is the postorder traversal of the same tree, reconstruct and return the binary tree. If there exist multiple answers, you can return any of them. Input: preorder …
Problem Statement Number of Dice Rolls With Target Sum LeetCode Solution – You have n dice and each die has k faces numbered from 1 to k. Given three integers n, k, and target, return the number of possible ways (out of the kn total ways) to roll the dice so the sum of the face-up numbers equals target. Since the answer may be …
Problem Statement Remove Duplicates from Sorted List II LeetCode Solution – Given the head of a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. Return the linked list sorted as well. Input: head = [1,2,3,3,4,4,5] Output: [1,2,5] Explanation The idea here is to traverse …
Problem Statement Shortest Path in a Grid with Obstacles Elimination LeetCode Solution – You are given an m x n integer matrix grid where each cell is either 0 (empty) or 1 (obstacle). You can move up, down, left, or right from and to an empty cell in one step. Return the minimum number of steps to walk from the upper left …
Problem Statement Can Place Flowers LeetCode Solution – You have a long flowerbed in which some of the plots are planted, and some are not. However, flowers cannot be planted in adjacent plots. Given an integer array flowerbed containing 0‘s and 1‘s, where 0 means empty and 1 means not empty, and an integer n, return if n new flowers can be planted in …
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 Analyze User Website Visit Pattern LeetCode Solution – You are given two string arrays username and website and an integer array timestamp. All the given arrays are of the same length and the tuple [username[i], website[i], timestamp[i]] indicates that the user username[i] visited the website website[i] at time timestamp[i]. A pattern is a list of three websites (not necessarily distinct). For example, [“home”, …
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 : Closest Binary Search Tree Value Leetcode Solution – Given the root of a binary search tree and a target value, return the value in the BST that is closest to the target. Example : Example 1 Input: root = [4,2,5,1,3], target = 3.714286 Output: 4 Example 2 Input: root = [1], target …
Problem Statement : Partition List Leetcode Solution – Given the head of a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x. You should preserve the original relative order of the nodes in each of the two partitions. Example : Example 1 Input: head = …