Array Trapping Rain Water Solution Java Problem Statement Given an a list of n integers which are non negative and represent an elevation map of various buildings where the width of each bar/building is 1, Find out how

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 Find Two Numbers in an Array Which Sum Up to K Problem Statement Given an array of integers, find out two indices such that the sum of the numbers at that indices matches K. For example, {4, 6, 8, 1, 9} and K = 15,

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

Array Best Time to Buy and Sell Stock Problem Statement Given an array 'stocks' in which each value at index 'i' is the stock price on day 'i', Find the maximum profit you can make by performing atmost one Buy and

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

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

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

Array Climbing Stairs Leetcode Problem Statement You are climbing a stair case. It takes n steps to reach to the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can