Leetcode Medium Longest Palindromic Substring Java Problem Statement Given a string, Find the longest palindromic substring. Solution Explanation Understanding the question here is very simple, given a string RENTNOW, the substring NTN is a palindrome of length 3, and

Array Find K Pairs with Smallest Sum Java Solution Problem Statement Given two integer arrays, arr1 and arr2, find K pairs of elements such that (x,y) where x is the value from the first array and y is the value from

Array Check If a Sudoku is Valid Problem Statement Determine if a sudoku is Valid. Solution Explanation Given a sudoku grid, we need to verify if the already filled in numbers doesn't violate the sudoku rules. The rules are very

Math Generate all Factor Combinations Problem Statement Given a number 'n', generate all factor combinations. For example, when n=24, the result would be [[2, 3, 3], [2, 9], [3, 6]] Solution Explanation As we know, every integer

Leetcode Medium Find Inorder Successor in a Binary Search Tree Problem Statement Given a binary search tree and the value of a certain node, find the next node in the inorder sequence after the given node. Solution Explanation The important information here is

Array Number of Islands Leetcode Problem Statement Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or

Math Find the Celebrity Problem Statement Suppose you are at a party with n people (labeled from 0 to n - 1) and among them, there may exist one celebrity. The definition of a celebrity is that

Array Three Sum(3Sum) Leetcode Problem Statement Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the

Array Meeting Rooms Leetcode Problem Statement Given an array of meeting time intervals consisting of start and end times [[s1,e1],[s2,e2],...] (si < ei), find the minimum number of conference rooms required. For example, Given

String Decode Ways Leetcode Problem Statement A message containing letters from A-Z is being encoded to numbers using the following mapping: 'A' -> 1 'B' -> 2 ... 'Z' -> 26 Given an encoded message

String Letter Combinations of a Phone Number Problem Statement Given a digit string, return all possible letter combinations that the number could represent. Input:Digit string "23" Output: ["ad", "ae", "af", "

Binary Tree Binary Tree Vertical Order Traversal Leetcode Problem Statement Given a binary tree, return the vertical order traversal of its nodes' values. (ie, from top to bottom, column by column). Solution Explanation Given a binary tree, 35 / \ 23 27 / \ \ 14

Array Sparse Matrix Multiplication Problem Statement Given two sparse matrices A and B, return the result of AB. You may assume that A's column number is equal to B's row number. Solution Explanation A sparse matrix is