Finding the Lucky Numbers in a Matrix
Given a m * n matrix of distinct numbers, return all lucky numbers in the matrix in any order. A lucky number is an element of the matrix such …
Factory Design Pattern in Object Oriented Design Programming
In OOP (Object Oriented Programming), we use inheritance to achieve the polymorphism. The factory design pattern allows you to create/manage different types of classes in a single place. Let’s …
Algorithm to Find Minimum Removals to Make Valid Parentheses
Given a string s of ‘(‘ , ‘)’ and lowercase English characters. Your task is to remove the minimum number of parentheses ( ‘(‘ or ‘)’, in any positions …
Greedy Algorithm to Validate Stack Sequences
Given two sequences pushed and popped with distinct values, return true if and only if this could have been the result of a sequence of push and pop operations …
Depth First Search Algorithm with Hash Set to Find Elements in a Contaminated Binary Tree
Given a binary tree with the following rules: root.val == 0 If treeNode.val == x and treeNode.left != null, then treeNode.left.val == 2 * x + 1 If treeNode.val …
Algorithms to Count How Many Numbers Are Smaller Than the Current Number
Given the array nums, for each nums find out how many numbers in the array are smaller than it. That is, for each nums you have to count the …