Problem Given two integer arrays inorder and postorder where inorder is the inorder traversal of a binary tree and postorder is the postorder traversal of the same tree, construct and return the binary tree. Example Example 1: 3 / \ 9 20 / \ 15 7 ...
Problem Given two integer arrays preorder and inorder where preorder is the preorder traversal of a binary tree and inorder is the inorder traversal of the same tree, construct and return the binary tree. Examples Example 1: 3 / \ 9 20 / \ 15 7 ...
Problem Given the head of a singly linked list where elements are sorted in ascending order, convert it to a height-balanced binary search tree. A height balanced BST: a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1. Examples Example 1: Input: nums = [1, 2, 3, 4, 5, 6] Output: [3,2,5,1,null,4,6] Explanation: [4,2,5,1,3,null,6] is also accepted. ...
Count Primes Problem Given an integer n, return the number of prime numbers that are strictly less than n. Examples Example 1: Input: n = 10 Output: 4 Explanation: There are 4 prime numbers less than 10, they are 2, 3, 5, 7. ...
Problem Given a string expression of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. You may return the answer in any order. Examples Example 1: Input: expression = "2-1-1" Output: [0,2] Explanation: ((2-1)-1) = 0 (2-(1-1)) = 2 ...
Problem Numbers can be regarded as product of its factors. For example, 8 = 2 x 2 x 2; = 2 x 4. Write a function that takes an integer n and return all possible combinations of its factors. Note: You may assume that n is always positive. Factors should be greater than 1 and less than n. Examples Example 1: ...
Find First Unique Character From a Stream of Characters Problem Given a string A denoting a stream of lowercase alphabets. You have to make new string B. B is formed such that we have to find first non-repeating character each time a character is inserted to the stream and append it at the end to B. If no non-repeating character is found then append ’#’ at the end of B. ...
Problem Write a method to shuffle a deck of cards. It must be a perfect shuffle – in other words, each 52! permutations of the deck has to be equally likely. Assume that you are given a random number generator which is perfect. OR How can you shuffle an array in O(n) time and O(1) space? For example, if input is an array of (1, 2, 3, 4, 5), one of the output can be (5, 4, 3, 2, 1) or (4, 2, 3, 1, 5). ...
Problem The chess knight has a unique movement, it may move two squares vertically and one square horizontally, or two squares horizontally and one square vertically (with both forming the shape of an L). The possible movements of chess knight are shown in this diagaram: A chess knight can move as indicated in the chess diagram below: ...
kSum Problem Problem Given an array S of n integers, are there elements a1, a2, a3…ak in S such that sum(a1, a2, a3, ... ak) = target? Find all unique lists in the array which gives the sum of target. Examples Refer problems like 4Sum, 3Sum - Classic Problem, 3Sum0 - Find three elements in an array that sum to a zero for examples. ...