Given an array of integers, return indices of the two numbers such that they add up to a specific target.

Given an array of strings strs, group the anagrams together. You can return the answer in any order.

Given an integer array nums and an integer k, return the k most frequent elements.

Find the length of the longest consecutive elements sequence in O(n) time.

Design an algorithm to encode a list of strings to a string. The encoded string is then sent over the network and is decoded back to the original list of strings.

Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k.

Given a large integer represented as an integer array digits, increment the large integer by one and return the resulting array of digits.

Given an array nums of n integers where nums[i] is in the range [1, n], return an array of all the integers in the range [1, n] that do not appear in nums. You must write an algorithm that runs in O(n) time and uses only constant extra space.

Given an integer array nums, return an integer array counts where counts[i] is the number of smaller elements to the right of nums[i].

Given an m x n board of characters and a list of strings words, return all words on the board.

Given a string s, partition s such that every substring of the partition is a palindrome. Return all possible palindrome partitioning of s.

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the answer in any order.

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

Given a string s that contains parentheses and letters, remove the minimum number of invalid parentheses to make the input string valid. Return all possible results.

Given a string num that contains only digits and an integer target, return all possible expressions by adding the binary operators +, -, or * between the digits so that the expression evaluates to the target value.

Koko loves to eat bananas. There are n piles of bananas, the ith pile has piles[i] bananas. The guards have gone and will come back in h hours. Koko can decide her bananas-per-hour eating speed of k. Each hour, she chooses some pile of bananas and eats k bananas from that pile. If the pile has less than k bananas, she eats all of them instead and will not eat any more bananas during this hour. Return the minimum integer k such that she can eat all the bananas within h hours.

Design a time-based key-value data structure that can store multiple values for the same key at different time stamps and retrieve the key's value at a certain timestamp.

Given an n x n matrix where each of the rows and columns is sorted in ascending order, return the kth smallest element in the matrix. Note that it is the kth smallest element in the sorted order, not the kth distinct element.

A peak element is an element that is strictly greater than its neighbors. Given a 0-indexed integer array nums, find a peak element, and return its index. If the array contains multiple peaks, return the index to any of the peaks.

Given two sorted arrays nums1 and nums2 of size m and n respectively, return the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).

A conveyor belt has packages that must be shipped from one port to another within days days. The ith package has a weight of weights[i]. Each day, we load the ship with packages on the conveyor belt (in the order given by weights). We may not load more weight than the maximum weight capacity of the ship. Return the least weight capacity of the ship that will result in all the packages on the conveyor belt being shipped within days days.

Given an integer array nums and an integer m, split the array into m non-empty continuous subarrays. Write an algorithm to minimize the largest sum among these m subarrays.

Given a sorted array, find the k closest integers to x. The result should also be sorted in ascending order.

You are a product manager and currently leading a team to develop a new product. Since each version is developed based on the previous version, all the versions after a bad version are also bad. Find the first bad version.

Given an integer n, return true if it is a power of two. Otherwise, return false.

Given an integer array nums, return the maximum result of nums[i] XOR nums[j], where 0 <= i <= j < n.

Design a data structure that follows the constraints of a Least Recently Used (LRU) cache. Implement the LRUCache class with get(key) returning the value or -1 if not found, and put(key, value) to insert or update. When capacity is exceeded, evict the least recently used key.

Design and implement a data structure for a Least Frequently Used (LFU) cache. Implement get and put operations with O(1) time complexity.

Given a data stream input of non-negative integers, summarize the numbers seen so far as a list of disjoint intervals.

Design an in-memory file system to simulate ls, mkdir, addContentToFile, and readContentFromFile operations.

Given a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words.

You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money. Return the fewest number of coins that you need to make up that amount. If that amount of money cannot be made up by any combination of the coins, return -1.

Given an integer array nums, return the length of the longest strictly increasing subsequence.

There is a robot on an m x n grid. The robot is 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. Given the two integers m and n, return the number of possible unique paths that the robot can take to reach the bottom-right corner.

Given two strings text1 and text2, return the length of their longest common subsequence. If there is no common subsequence, return 0.

Given two strings word1 and word2, return the minimum number of operations required to convert word1 to word2. Operations: insert, delete, or replace a character.

You are given an integer array nums and an integer target. You want to build an expression out of nums by adding one of the symbols '+' and '-' before each integer in nums. Return the number of different expressions that you can build, which evaluates to target.

Find the maximum profit with a cooldown period of 1 day after selling (cannot buy the next day after selling).

You are given an integer array prices where prices[i] is the price of a given stock on the ith day, and an integer k. Find the maximum profit you can achieve. You may complete at most k transactions. Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).

Given a string containing just the characters '(' and ')', return the length of the longest valid (well-formed) parentheses substring.

You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money. Return the number of combinations that make up that amount. If that amount of money cannot be made up by any combination of the coins, return 0.

Given an m x n binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area.

Given an input string (s) and a pattern (p), implement wildcard pattern matching with support for '?' and '*' where: '?' Matches any single character. '*' Matches any sequence of characters (including the empty sequence).

Given an m x n integers matrix, return the length of the longest increasing path in matrix. From each cell, you can either move in four directions: left, right, up, or down. You may not move diagonally or move outside the boundary.

The demons had captured the princess and imprisoned her in the bottom-right corner of a dungeon. The dungeon consists of m x n rooms. Our valiant knight was initially positioned in the top-left room and must fight through the dungeon to rescue the princess. The knight has an initial health point. Some rooms have demons that decrease health, others have magic orbs that increase health. Determine the minimum initial health needed so the knight can rescue the princess.

You are given n balloons, indexed from 0 to n - 1. Each balloon is painted with a number on it represented by an array nums. You are asked to burst all the balloons. If you burst the ith balloon, you will get nums[i - 1] * nums[i] * nums[i + 1] coins. If i - 1 or i + 1 goes out of bounds, treat it as if there is a balloon with a 1 painted on it. Return the maximum coins you can collect by bursting the balloons wisely.

You are given an array of binary strings strs and two integers m and n. Return the size of the largest subset of strs such that there are at most m 0's and n 1's in the subset.

Given an input string s and a pattern p, implement regular expression matching with support for '.' and '*' where: '.' Matches any single character. '*' Matches zero or more of the preceding element. The matching should cover the entire input string (not partial).

Given a rows x cols binary matrix filled with 0's and 1's, find the largest rectangle containing only 1's and return its area.

Given a string s and a dictionary of strings wordDict, add spaces in s to construct a sentence where each word is a valid dictionary word. Return all such possible sentences in any order.

You are given a 2D array of integers envelopes where envelopes[i] = [wi, hi] represents the width and height of an envelope. Return the maximum number of envelopes you can Russian doll (i.e., put one inside other).

We have n jobs, where every job is scheduled to be done from startTime[i] to endTime[i], obtaining a profit of profit[i]. Return the maximum profit you can take such that there are no two jobs with overlapping time ranges.

You are given k identical eggs and you have access to a building with n floors. Your goal is to determine the minimum number of moves needed to find the critical floor f where eggs start breaking.

You are given an integer array arr. From some starting index, you can make a series of jumps. The first jump is odd, the second is even, and so on. From index i, during odd jumps you can jump to j where arr[j] is the smallest value >= arr[i] with j > i. During even jumps, jump to j where arr[j] is the largest value <= arr[i] with j > i. Return the number of good starting indices.

You are given a rows x cols matrix grid representing a field of cherries where grid[i][j] represents the number of cherries you can collect from cell (i, j). Two robots are located at (0, 0) and (0, cols-1). Return the maximum number of cherries collected using both robots by moving towards the bottom.

A frog is crossing a river. The river is divided into some number of units, and at each unit, there may or may not exist a stone. The frog can jump on a stone, but it must not jump into the water. Given a list of stones positions in sorted ascending order, determine if the frog can cross the river by landing on the last stone. Initially, the frog is on the first stone and assumes the first jump must be 1 unit.

Given a rectangular pizza represented as a rows x cols matrix containing 'A' (apple) and '.', cut the pizza into k pieces using k-1 cuts. For each cut, you choose the direction: horizontal or vertical, then cut the pizza. The piece given away is either the upper part if horizontal or the left part if vertical. Return the number of ways to cut such that each piece contains at least one apple.

A strange printer can only print a sequence of the same character each turn. At each turn, the printer can print new characters starting from and ending at any place and will cover the original existing characters. Given a string s, return the minimum number of turns the printer needs to print it.

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.

Given a reference of a node in a connected undirected graph. Return a deep copy (clone) of the graph.

There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, bi] indicates that you must take course bi first if you want to take course ai. Return true if you can finish all courses. Otherwise, return false.

Return a list of grid coordinates where water can flow to both the Pacific and Atlantic oceans.

You have a graph of n nodes. You are given an integer n and an array edges where edges[i] = [ai, bi] indicates that there is an edge between ai and bi in the graph. Return the number of connected components in the graph.

Given n nodes labeled from 0 to n - 1 and a list of undirected edges, write a function to check whether these edges make up a valid tree.

In this problem, a tree is an undirected graph that is connected and has no cycles. You are given a graph that started as a tree with n nodes labeled from 1 to n, with one additional edge added. The added edge has two different vertices chosen from 1 to n, and was not an edge that already existed. The graph is represented as an array edges of length n where edges[i] = [ai, bi] indicates that there is an edge between nodes ai and bi in the graph. Return an edge that can be removed so that the resulting graph is a tree of n nodes. If there are multiple answers, return the answer that occurs last in the input.

You are given an m x n binary matrix grid. An island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical). Return the maximum area of an island in grid. If there is no island, return 0.

You are given an m x n grid where each cell can have one of three values: 0 (empty), 1 (fresh orange), or 2 (rotten orange). Every minute, any fresh orange that is 4-directionally adjacent to a rotten orange becomes rotten. Return the minimum number of minutes until no cell has a fresh orange. If impossible, return -1.

There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, bi] indicates that you must take course bi first if you want to take course ai. Return the ordering of courses you should take to finish all courses. If there are many valid answers, return any of them. If it is impossible to finish all courses, return an empty array.

Given an m x n matrix board containing 'X' and 'O', capture all regions that are 4-directionally surrounded by 'X'. A region is captured by flipping all 'O's into 'X's in that surrounded region.

Given two words beginWord and endWord, and a dictionary wordList, return the number of words in the shortest transformation sequence from beginWord to endWord (changing one letter at a time).

Given a list of accounts where each account contains a name and emails, merge accounts belonging to the same person (accounts that share at least one common email).

There is a new alien language that uses the English alphabet. However, the order among the letters is unknown to you. You are given a list of strings words from the alien language's dictionary, where the strings in words are sorted lexicographically by the rules of this new language. Return a string of the unique letters in the new alien language sorted in lexicographically increasing order by the new rules. If there is no solution, return "".

You are given an array points representing integer coordinates of some points on a 2D-plane, where points[i] = [xi, yi]. The cost of connecting two points [xi, yi] and [xj, yj] is the manhattan distance between them: |xi - xj| + |yi - yj|. Return the minimum cost to make all points connected.

You are given a network of n nodes, labeled from 1 to n. You are also given times, a list of travel times as directed edges times[i] = (ui, vi, wi), where ui is the source node, vi is the target node, and wi is the time it takes for a signal to travel from source to target. We send a signal from a given node k. Return the minimum time it takes for all the n nodes to receive the signal. If it is impossible for all the n nodes to receive the signal, return -1.

You are given a list of airline tickets where tickets[i] = [fromi, toi] represent the departure and the arrival airports of one flight. Reconstruct the itinerary in order and return it.

There is an undirected graph with n nodes, where each node is numbered between 0 and n - 1. You are given a 2D array graph, where graph[u] is an array of nodes that node u is adjacent to. Return true if and only if it is bipartite.

You are given an array of variable pairs equations and an array of real numbers values, where equations[i] = [Ai, Bi] and values[i] represent the equation Ai / Bi = values[i]. Each Ai or Bi is a string that represents a single variable. You are also given some queries, where queries[j] = [Cj, Dj] represents the jth query where you must find the answer for Cj / Dj = ?. Return the answers to all queries.

You are a hiker preparing for an upcoming hike. You are given heights, a 2D array of size rows x columns, where heights[row][col] represents the height of cell (row, col). You are situated in the top-left cell, (0, 0), and you hope to travel to the bottom-right cell, (rows-1, columns-1). The effort required to travel from one cell to an adjacent cell is the absolute difference of their heights. Return the minimum effort required to travel from the top-left cell to the bottom-right cell.

You are given an n x n integer matrix grid where each value grid[i][j] represents the elevation at that point (i, j). The rain starts to fall. At time t, the depth of the water everywhere is t. You can swim from a square to another 4-directionally adjacent square if and only if the elevation of both squares individually are at most t. You can swim infinite distances in zero time. Return the least time until you can reach the bottom right square (n - 1, n - 1) starting from the top left square (0, 0).

A tree is an undirected graph in which any two vertices are connected by exactly one path. Given a tree of n nodes labelled from 0 to n - 1, and an array of n - 1 edges, you can choose any node of the tree as the root. The height of a rooted tree is the number of edges on the longest downward path between the root and a leaf. Return a list of all MHTs root labels. You can return the answer in any order.

There are n servers numbered from 0 to n - 1 connected by undirected server-to-server connections forming a network where connections[i] = [ai, bi] represents a connection between servers ai and bi. Any server can reach other servers directly or indirectly through the network. A critical connection is a connection that, if removed, will make some servers unable to reach some other server. Return all critical connections in the network in any order.

On a 2D plane, we place n stones at some integer coordinate points. Each coordinate point may have at most one stone. A stone can be removed if it shares either the same row or the same column as another stone that has not been removed. Given an array stones of length n where stones[i] = [xi, yi] represents the location of the ith stone, return the largest possible number of stones that can be removed.

In this problem, a rooted tree is a directed graph such that, there is exactly one node (the root) for which all other nodes are descendants of this node, plus every node has exactly one parent, except for the root node which has no parents. The given input is a directed graph that started as a rooted tree with n nodes (with distinct values from 1 to n), with one additional directed edge added. Return an edge that can be removed so that the resulting graph is a rooted tree of n nodes.

An n x n grid is composed of 1 x 1 squares where each 1 x 1 square consists of a '/', '\', or blank space ' '. These characters divide the square into contiguous regions. Given the grid grid represented as a string array, return the number of regions.

A transformation sequence from word beginWord to word endWord using a dictionary wordList is a sequence of words beginWord -> s1 -> s2 -> ... -> sk such that every adjacent pair differs by a single letter, every si is in wordList, and sk == endWord. Given two words and a dictionary, return all the shortest transformation sequences.

N couples sit in 2N seats arranged in a row. You want every couple to sit side by side. Couples are numbered (0,1), (2,3), etc. A swap consists of choosing any two people and having them swap seats. Return the minimum number of swaps so that every couple is sitting side by side.

Given an array routes where routes[i] is a bus route that the ith bus repeats forever. You start at bus stop source and want to go to bus stop target. Return the least number of buses you must take to travel from source to target, or -1 if impossible.

Given a m x n grid where -1 is a wall, 0 is a gate, and INF (2147483647) is an empty room. Fill each empty room with the distance to its nearest gate. If impossible to reach a gate, leave it as INF.

You are given a string s. We want to partition the string into as many parts as possible so that each letter appears in at most one part. Return a list of integers representing the size of these parts.

Alice has some number of cards and she wants to rearrange the cards into groups so that each group is of size groupSize, and consists of groupSize consecutive cards. Given an integer array hand where hand[i] is the value written on the ith card and an integer groupSize, return true if she can rearrange the cards, or false otherwise.

A triplet is an array of three integers. You are given a 2D integer array triplets, where triplets[i] = [ai, bi, ci]. You are also given an integer array target = [x, y, z] that describes the triplet you want to obtain. To obtain target, you may apply the following operation on triplets any number of times (possibly zero): Choose two indices (0-indexed) i and j (i != j) and update triplets[j] to become [max(ai, aj), max(bi, bj), max(ci, cj)]. Return true if it is possible to obtain the target triplet [x, y, z] as an element of triplets, or false otherwise.

There are n gas stations along a circular route, where the amount of gas at the ith station is gas[i]. You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from the ith station to its next (i + 1)th station. You begin the journey with an empty tank at one of the gas stations. Return the starting gas station's index if you can travel around the circuit once in the clockwise direction, otherwise return -1.

You are given an array of people, people, which are the attributes of some people in a queue (not necessarily in order). Each people[i] = [hi, ki] represents the ith person of height hi with exactly ki other people in front who have a height >= hi. Reconstruct and return the queue that is represented by the input array.

The median is the middle value in an ordered integer list. Implement the MedianFinder class.

Given a string s, rearrange the characters of s so that any two adjacent characters are not the same. Return any possible rearrangement of s or return "" if not possible.

Given a characters array tasks, representing the tasks a CPU needs to do, where each letter represents a different task. Tasks could be done in any order. Each task is done in one unit of time. For each unit of time, the CPU could complete either one task or just be idle. However, there is a non-negative integer n that represents the cooldown period between two same tasks (the same letter in the array), that is that there must be at least n units of time between any two same tasks.

You have a collection of stones with positive integer weights. Each turn, choose the two heaviest stones and smash them. If they have different weights, the lighter one is destroyed and the heavier one loses weight equal to the lighter. Return the weight of the last remaining stone, or 0 if none remain.

Given an array of points where points[i] = [xi, yi] represents a point on the X-Y plane and an integer k, return the k closest points to the origin (0, 0). The distance between two points is the Euclidean distance. You may return the answer in any order.

Given an integer array nums and an integer k, return the kth largest element in the array. Note that it is the kth largest element in the sorted order, not the kth distinct element.

A city's skyline is the outer contour of the silhouette formed by all the buildings in that city when viewed from a distance. Given the locations and heights of all the buildings, return the skyline formed by these buildings collectively.

You have k lists of sorted integers. Find the smallest range that includes at least one number from each of the k lists.

A car travels from a starting position to a destination which is target miles east. Along the way, there are gas stations. Return the minimum number of refueling stops the car must make to reach destination. If it cannot reach the destination, return -1.

Given an array nums and an integer k, return an array of the median of each window of size k moving from left to right.

Given an array of intervals intervals where intervals[i] = [starti, endi], return the minimum number of intervals you need to remove to make the rest of the intervals non-overlapping.

Given an array of meeting time intervals consisting of start and end times [[s1,e1],[s2,e2],...] (si < ei), determine if a person could attend all meetings.

Given an array of meeting time intervals consisting of start and end times [[s1,e1],[s2,e2],...] (si < ei), find the minimum number of conference rooms required.

You are given an array of non-overlapping intervals intervals where intervals[i] = [starti, endi] represent the start and the end of the ith interval and intervals is sorted in ascending order by starti. You are also given an interval newInterval = [start, end] that represents the start and end of another interval. Insert newInterval into intervals such that intervals is still sorted in ascending order by starti and intervals still does not have any overlapping intervals (merge overlapping intervals if necessary).

Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cover all the intervals in the input.

You are given an integer n. There are n rooms numbered from 0 to n - 1. You are given a 2D integer array meetings where meetings[i] = [starti, endi] means that a meeting will be held during the closed time interval [starti, endi]. All the values of starti are unique. Return the room number that held the most meetings.

Given the head of a linked list, remove the nth node from the end of the list and return its head.

You are given an array of k linked-lists lists, each linked-list is sorted in ascending order. Merge all the linked-lists into one sorted linked-list and return it.

Implement pow(x, n), which calculates x raised to the power n (i.e., x^n). Use the fast exponentiation algorithm to achieve O(log n) time complexity.

Write an algorithm to determine if a number n is happy. A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1.

Given an m x n matrix, return all elements of the matrix in spiral order.

Given a string s, find the length of the longest substring without repeating characters.

You are given a string s and an integer k. You can choose any character of the string and change it to any other uppercase English character. You can perform this operation at most k times. Return the length of the longest substring containing the same letter you can get after performing the above operations.

You are given an array of integers nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k numbers in the window. Each time the sliding window moves right by one position. Return the max sliding window.

Given two strings s and p, return an array of all the start indices of p's anagrams in s. You may return the answer in any order.

Given two strings s and t of lengths m and n respectively, return the minimum window substring of s such that every character in t (including duplicates) is included in the window. If there is no such substring, return the empty string "".

Given a string s and an integer k, return the length of the longest substring of s that contains at most k distinct characters.

Given a string s containing just the characters "(", ")", "{", "}", "[" and "]", determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order.

Given an array of integers temperatures represents the daily temperatures, return an array answer such that answer[i] is the number of days you have to wait after the ith day to get a warmer temperature. If there is no future day for which this is possible, keep answer[i] == 0.

There are n cars going to the same destination along a one-lane road. The destination is target miles away. You are given two integer arrays position and speed, both of length n, where position[i] is the position of the ith car and speed[i] is the speed of the ith car (in miles per hour). A car can never pass another car ahead of it, but it can catch up to it and drive bumper to bumper at the same speed. The distance between these two cars is ignored - they are assumed to have the same position. A car fleet is some non-empty set of cars driving at the same position and same speed. Note that a single car is also a car fleet. If a car catches up to a car fleet at the destination point, it will still be considered as one car fleet. Return the number of car fleets that will arrive at the destination.

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.

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.

Given string num representing a non-negative integer num, and an integer k, return the smallest possible integer after removing k digits from num.

Given an array of asteroids, find out the state after all collisions. Positive means moving right, negative means moving left. The larger asteroid survives.

Given a string s representing a valid expression, implement a basic calculator to evaluate it, and return the result of the evaluation. The expression string may contain open ( and closing ) parentheses, the plus + or minus - sign, non-negative integers and empty spaces.

Given an encoded string, return its decoded string. The encoding rule is: k[encoded_string], where the encoded_string inside the square brackets is being repeated exactly k times.

Given two strings s and t, determine if they are isomorphic. Two strings are isomorphic if the characters in s can be replaced to get t.

You are given a string s. You can convert s to a palindrome by adding characters in front of it. Return the shortest palindrome you can find by performing this transformation.

Given an array of words and a maxWidth, format the text such that each line has exactly maxWidth characters and is fully (left and right) justified.

Given the root of a binary tree, invert the tree, and return its root.

Design an algorithm to serialize and deserialize a binary tree. There is no restriction on how your serialization/deserialization algorithm should work.

Given the root of a binary tree, return the length of the diameter of the tree.

Given the root of a binary tree, return the maximum width of the given tree. The maximum width of a tree is the maximum width among all levels. The width of one level is defined as the length between the end-nodes (the leftmost and rightmost non-null nodes), where the null nodes between the end-nodes that would be present in a complete binary tree are also counted.

Implement the BSTIterator class that represents an iterator over the in-order traversal of a binary search tree (BST). The class should have a constructor that takes the root of a BST, a next() method that returns the next smallest number, and a hasNext() method that returns whether there is a next number.

Given an integer array nums, handle multiple queries of the following types: Update the value of an element in nums. Calculate the sum of the elements of nums between indices left and right inclusive where left <= right. Implement the NumArray class with update(index, val) and sumRange(left, right) methods.

You are given the root of a binary tree. We install cameras on the tree nodes where each camera at a node can monitor its parent, itself, and its immediate children. Return the minimum number of cameras needed to monitor all nodes of the tree.

Given a tree represented by parent array and a string s where s[i] is the character assigned to node i, return the length of the longest path where adjacent nodes have different characters.

A trie (prefix tree) is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. Implement the Trie class with insert, search, and startsWith methods.

Design a data structure that supports adding new words and finding if a string matches any previously added string. Implement the WordDictionary class with addWord(word) and search(word) methods. search(word) can search a literal word or a regular expression string containing only letters a-z or '.'. A '.' means it can represent any one letter.

Given a list of unique words, return all pairs of distinct indices (i, j) such that the concatenation of words[i] + words[j] is a palindrome.

Given an array of strings words (without duplicates), return all the concatenated words in the given list. A concatenated word is a string that is comprised entirely of at least two shorter words in the given array.

Design a special dictionary that searches words by a prefix and a suffix. Implement WordFilter with constructor that takes words array, and f(prefix, suffix) that returns the index of the word with given prefix and suffix. If multiple words match, return the largest index.

Find two lines that together with the x-axis form a container, such that the container contains the most water.

Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining.

Given a string s, return true if the s can be palindrome after deleting at most one character from it.