Given the root of a binary tree, return the most frequent subtree sum.If there is a tie, return all the values with the highest frequency in any order.The subtree sum of a node is defined as the sum of all the node values formed by the subtree rooted at that node (including the node itself)….

Design a data structure that simulates an in-memory file system. Implement the FileSystem class: Example:FileSystem fileSystem = new FileSystem();fileSystem.ls(“/”); // return []fileSystem.mkdir(“/a/b/c”);fileSystem.ls(“/”); // return [“a”] This problem tests your ability to design a hierarchical data structure that behaves like a real file system. The core idea is to represent directories using a tree-like structure, where…

Problem: Maximum Product Subarray Given an integer array nums, find the contiguous subarray within an array (containing at least one number) which has the largest product, and return the product. Example:Input:nums = [2,3,-2,4]Output:6Explanation:The subarray [2,3] has the largest product 6. Constraints:1 <= nums.length <= 2 * 10^4-10 <= nums[i] <= 10The product of any prefix…

TikTok is hosting a livestream event with popular creators. Each creator has submitted their preferred start time and end time for their part in the livestream. Only one creator can livestream at the event at a time. Given an array of available time intervals where intervals[i] = [start(i), end(i)], determine if all creators could attend…

Maximum SubarrayGiven an integer array nums[], find the subarray with the largest sum, and return its sum. Input:nums = [-2,1,-3,4,-1,2,1,-5,4]Output:6Explanation:The subarray [4,-1,2,1] has the largest sum 6. This problem is about finding the maximum possible sum among all non-empty contiguous subarrays. The key idea is to scan from left to right and decide at each…

Given an array of integers heights representing the histogram’s bar height where the width of each bar is 1, return the area of the largest rectangle in the histogram. Input:heights = [2,1,5,6,2,3]Output:10 This problem asks you to determine the maximum rectangular area that can be formed within a histogram. A brute-force approach would check every…

You are given two integer arrays preorder and inorder where: Return the postorder traversal (left → right → root) of the tree. Example:Input:preorder = [1,2,4,5,3,6]inorder = [4,2,5,1,3,6]Output:[4,5,2,6,3,1] This problem revolves around reconstructing the traversal logic of a binary tree using two known traversal orders. The key insight is that preorder gives you the root first,…

Given shape D: [d0, d1, d2, … dm-1] and a 1-d index, output the corresponding coordinates. inputs:shape: (2, 3)1-d index: 3output:[1, 0] This problem asks you to convert a flattened one-dimensional index back into its corresponding multi-dimensional coordinates based on the given shape. The key idea is to understand how multi-dimensional arrays are stored in…

For an array of n positive integers arr[n] and an integer k, a subarray is considered good if it consists of at least k distinct integers. Find the minimum length subarray that is good. If there is no such subarray, return -1. Example:arr = [2, 2, 1, 1, 3]k = 3 The subarrays with at…

Given an m x n 2D binary grid grid which represents a map of ‘1’s (land) and ‘0’s (water), return the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water. This…