1982. Find Array Given Subset Sums

Problem You are given an integer n representing the length of an unknown array that you are trying to recover. You are also g...

hard difficult

782. Transform to Chessboard

Problem You are given an n x n binary grid board. In each move, you can swap any two rows with each other, or any two columns...

hard

2056. Number of Valid Move Combinations On Chessboard

Problem There is an 8 x 8 chessboard containing n pieces (rooks, queens, or bishops). You are given a string array pieces of ...

hard

52. N-Queens II

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 oth...

hard

1531. String Compression II

Problem Run-length encoding is a string compression method that works by replacing consecutive identical characters (repeated...

hard difficult

51. N-Queens

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 oth...

hard

2097. Valid Arrangement of Pairs

Problem You are given a 0-indexed 2D integer array pairs where pairs[i] = [startᵢ, endᵢ]. An arrangement of pairs is valid if...

hard todo

2577. Minimum Time to Visit a Cell In a Grid

Problem You are given a m x n matrix grid consisting of non-negative integers where grid[row][col] represents the minimum tim...

hard

3251. Find the Count of Monotonic Pairs II

跟 3250. Find the Count of Monotonic Pairs I 一模一样,只不过 nums[i] 的上限从 50 增加到 1000。 https://leetcode.cn/problems/find-the-count-of...

hard

3250. Find the Count of Monotonic Pairs I

Problem You are given an array of positive integers nums of length n. We call a pair of non-negative integer arrays (arr1, ar...

hard

2290. Minimum Obstacle Removal to Reach Corner

Problem You are given a 0-indexed 2D integer array grid of size m x n. Each cell has one of two values: 0 represents an empt...

hard

124. Binary Tree Maximum Path Sum

Problem A path in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecti...

hard

632. Smallest Range Covering Elements from K Lists

Problem You have k lists of sorted integers in non-decreasing order. Find the smallest range that includes at least one numbe...

hard

212. Word Search II

Problem Given an m x n board of characters and a list of strings words, return all words on the board. Each word must be cons...

hard

76. Minimum Window Substring

Problem Given two strings s and t of lengths m and n respectively, return the minimum window substring of s such that every c...

hard

3244. Shortest Distance After Road Addition Queries II

Problem You are given an integer n and a 2D integer array queries. There are n cities numbered from 0 to n - 1. Initially, th...

hard

300. Longest Increasing Subsequence

Problem Given an integer array nums, return the length of the longest strictly increasing subsequence. A subsequence is an a...

medium hard

297. Serialize and Deserialize Binary Tree

Problem Serialization is the process of converting a data structure or object into a sequence of bits so that it can be store...

hard

295. Find Median from Data Stream

Problem The median is the middle value in an ordered integer list. If the size of the list is even, there is no middle value,...

hard

23. Merge k Sorted Lists

Problem You are given an array of k linked-lists lists, each linked-list is sorted in ascending order. Merge all the linked-l...

hard

3261. Count Substrings That Satisfy K-Constraint II

Problem You are given a binary string s and an integer k. You are also given a 2D integer array queries, where queries[i] = [...

hard

1547. Minimum Cost to Cut a Stick

Problem Given a wooden stick of length n units. The stick is labelled from 0 to n. For example, a stick of length 6 is labell...

hard

3235. Check if the Rectangle Corner Is Reachable

Problem You are given two positive integers xCorner and yCorner, and a 2D array circles, where circles[i] = [xᵢ, yᵢ, rᵢ] deno...

hard difficult