Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST. According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between t

Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order. Example 1:Input: nums = [1,1,1,2,2,3], k = 2Output: [1,2] Example 2

A permutation of an array of integers is an arrangement of its members into a sequence or linear order. For example, for arr = [1,2,3], the following are all the permutations of arr: [1,2,3], [1,

Implement a last-in-first-out (LIFO) stack using only two queues. The implemented stack should support all the functions of a normal stack (push, top, pop, and empty). Implement the MyStack class:void

Implement a first in first out (FIFO) queue using only two stacks. The implemented queue should support all the functions of a normal queue (push, peek, pop, and empty). Implement the MyQueue class:vo

Design a data structure that follows the constraints of a Least Recently Used (LRU) cache. Implement the LRUCache class: LRUCache(int capacity) Initialize the LRU cache with positive size capacity. i

Given an integer array nums sorted in non-decreasing order, return an array of the squares of each number sorted in non-decreasing order. Example 1:Input: nums = [-4,-1,0,3,10]Output: [0,1,9,16,1

Given an m x n matrix mat, return an array of all the elements of the array in a diagonal order. Example 1:Input: mat = [[1,2,3],[4,5,6],[7,8,9]]Output: [1,2,4,7,5,3,6,8,9] Example 2:Input: mat &

Given an m x n integer matrix matrix, if an element is 0, set its entire row and column to 0’s. You must do it in place. Example 1:Input: matrix = [[1,1,1],[1,0,1],[1,1,1]]Output: [[1,0,1],[0,0,0

Given a positive integer n, generate an n x n matrix filled with elements from 1 to n2 in spiral order. Example 1:Input: n = 3Output: [[1,2,3],[8,9,4],[7,6,5]] Example 2:Input: n = 1Output: