Problem Statement Minimum Height Trees LeetCode Solution – We are given a tree of n nodes labelled from 0 to n-1 as a 2D array “edges” where edge[i] = [a_i, b_i] indicates that there is an undirected edge between the two nodes a_i and b_i in the tree. We have …
Problem Statement Kth Smallest Element in a Sorted Matrix LeetCode Solution – We are given a matrix of size n where each of the rows and columns is sorted in ascending order. We are asked to return the kth smallest element in the matrix. Note that it is the kth …
Problem Statement Number of Islands II LeetCode Solution – You are given an empty 2D binary grid grid of size m x n. The grid represents a map where 0‘s represent water and 1‘s represent land. Initially, all the cells grid are water cells (i.e., all the cells are 0‘s). We may perform an add land …
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 Race Car LeetCode Solution – Your car starts at the position 0 and speed +1 on an infinite number line. Your car can go into negative positions. Your car drives automatically according to a sequence of instructions ‘A’ (accelerate) and ‘R’ (reverse): When you get an instruction ‘A’, your car does the following: position += speed …
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 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 …