Problem Given a simple expression tree, consisting of basic binary operators i.e., + , – , * and / and some integers, evaluate the expression tree. Examples Example 1: graph TD; A(+) --- B(*) & C("-") B --- D(5) & E(4) C --- F(100) & G(20) Input: root = ["+", "*", "-", "5", "4", "100", "20"] Output: 100 ...
Problem The n-queens puzzle is the problem of placing n queens on an n x n chessboard such that no two queens attack each other. Given an integer n, return all distinct solutions to the n-queens puzzle. You may return the answer in any order. Each solution contains a distinct board configuration of the n-queens’ placement, where 'Q' and '.' both indicate a queen and an empty space, respectively. ...
Problem Given the head of a linked list, reverse the nodes of the list k at a time, and return the modified list. k is a positive integer and is less than or equal to the length of the linked list. If the number of nodes is not a multiple of k then left-out nodes, in the end, should remain as it is. You may not alter the values in the list’s nodes, only nodes themselves may be changed. ...
Problem There are n children standing in a line. Each child is assigned a rating value given in the integer array ratings. You are giving candies to these children subjected to the following requirements: Each child must have at least one candy. Children with a higher rating get more candies than their neighbors. Return the minimum number of candies you need to have to distribute the candies to the children. ...
Problem Given an array nums of size n, return the majority element. The majority element is the element that appears more than ⌊n / 2⌋ times. You may assume that the majority element always exists in the array. Definition Majority Element: If an element appears more than n/2 times in array where n is the size of the array. Examples int [] arrA = {1,3,5,5,5,5,4,1,5}; Output: Element appearing more than n/2 times: 5 int []arrA = {1,2,3,4}; Output: No element appearing more than n/2 times ...
Problem Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct. Examples Example 1: Input: nums = [1,2,3,1] Output: true Example 2: Input: nums = [1,2,3,4] Output: false ...
Problem Given a circular linked list, implement an algorithm which returns node at the beginning of the loop. If there is no cycle, return null. Try solving it using constant additional space. Definition - Circular Linked List A (corrupt) linked list in which a node’s next pointer points to an earlier node, so as to make a loop in the linked list. This is extension of Linked List Cycle 1 - Detect Cycle ...
Problem Given the head of a singly linked list, sort the list using insertion sort, and return the sorted list’s head. The steps of the insertion sort algorithm: Insertion sort iterates, consuming one input element each repetition and growing a sorted output list. At each iteration, insertion sort removes one element from the input data, finds the location it belongs within the sorted list and inserts it there. It repeats until no input elements remain. The following is a graphical example of the insertion sort algorithm. ...
Problem You are given an m x n integer array grid. There is a robot initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner (i.e., grid[m-1][n-1]). The robot can only move either down or right at any point in time. An obstacle and space are marked as 1 or 0 respectively in grid. A path that the robot takes cannot include any square that is an obstacle. ...
Problem Given a positive integer n, generate an n x n matrix filled with elements from 1 to n2 in spiral order. Examples Example 1: Input: n = 3 Output: [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ] Example 2: Input: n = 4 Output: [ [1, 2, 3, 4], [12, 13, 14, 5], [11, 16, 15, 6], [10, 9, 8, 7] ] ...