Hard LeetCode Problems: Page 3 of 4

Problems 401 to 600 of the 661 Hard-rated problems in this library, continuing the list on the Hard hub.

Page 3 of 4

Hard problems, page 3
No.	Problem	Topics
2360	Longest Cycle in a Graph	Depth-First Search, Breadth-First Search, Graph +1
2366	Minimum Replacements to Sort the Array	Greedy, Array, Math
2376	Count Special Integers	Math, Dynamic Programming
2382	Maximum Segment Sum After Removals	Union Find, Array, Ordered Set +1
2386	Find the K-Sum of an Array	Array, Sorting, Heap (Priority Queue)
2392	Build a Matrix With Conditions	Graph, Topological Sort, Array +1
2398	Maximum Number of Robots Within Budget	Queue, Array, Binary Search +4
2402	Meeting Rooms III	Array, Hash Table, Sorting +2
2407	Longest Increasing Subsequence II	Binary Indexed Tree, Segment Tree, Queue +4
2412	Minimum Money Required Before Transactions	Greedy, Array, Sorting
2416	Sum of Prefix Scores of Strings	Trie, Array, String +1
2421	Number of Good Paths	Tree, Union Find, Graph +3
2426	Number of Pairs Satisfying Inequality	Binary Indexed Tree, Segment Tree, Array +4
2430	Maximum Deletions on a String	String, Dynamic Programming, String Matching +2
2435	Paths in Matrix Whose Sum Is Divisible by K	Array, Dynamic Programming, Matrix
2440	Create Components With Same Value	Tree, Depth-First Search, Array +2
2444	Count Subarrays With Fixed Bounds	Queue, Array, Sliding Window +1
2448	Minimum Cost to Make Array Equal	Greedy, Array, Binary Search +2
2449	Minimum Number of Operations to Make Arrays Similar	Greedy, Array, Sorting
2454	Next Greater Element IV	Stack, Array, Binary Search +3
2458	Height of Binary Tree After Subtree Removal Queries	Tree, Depth-First Search, Breadth-First Search +2
2463	Minimum Total Distance Traveled	Array, Dynamic Programming, Sorting
2468	Split Message Based on Limit	String, Binary Search, Enumeration
2472	Maximum Number of Non-overlapping Palindrome Substrings	Greedy, Two Pointers, String +1
2478	Number of Beautiful Partitions	String, Dynamic Programming, Prefix Sum
2484	Count Palindromic Subsequences	String, Dynamic Programming
2488	Count Subarrays With Median K	Array, Hash Table, Prefix Sum
2493	Divide Nodes Into the Maximum Number of Groups	Depth-First Search, Breadth-First Search, Union Find +1
2499	Minimum Total Cost to Make Arrays Unequal	Greedy, Array, Hash Table +1
2503	Maximum Number of Points From Grid Queries	Breadth-First Search, Union Find, Array +4
2508	Add Edges to Make Degrees of All Nodes Even	Graph, Hash Table
2509	Cycle Length Queries in a Tree	Tree, Array, Binary Tree
2514	Count Anagrams	Hash Table, Math, String +2
2518	Number of Great Partitions	Array, Dynamic Programming
2528	Maximize the Minimum Powered City	Greedy, Queue, Array +3
2532	Time to Cross a Bridge	Array, Simulation, Heap (Priority Queue)
2538	Difference Between Maximum and Minimum Price Sum	Tree, Depth-First Search, Array +1
2543	Check if Point Is Reachable	Math, Number Theory
2547	Minimum Cost to Split an Array	Array, Hash Table, Dynamic Programming +1
2551	Put Marbles in Bags	Greedy, Array, Sorting +1
2552	Count Increasing Quadruplets	Binary Indexed Tree, Array, Dynamic Programming +2
2561	Rearranging Fruits	Greedy, Sort, Array +1
2565	Subsequence With the Minimum Score	Two Pointers, String, Binary Search
2569	Handling Sum Queries After Update	Segment Tree, Array
2573	Find the String with LCP	Greedy, Union Find, Array +3
2577	Minimum Time to Visit a Cell In a Grid	Breadth-First Search, Graph, Array +3
2581	Count Number of Possible Root Nodes	Tree, Depth-First Search, Array +2
2584	Split the Array to Make Coprime Products	Array, Hash Table, Math +1
2585	Number of Ways to Earn Points	Array, Dynamic Programming
2589	Minimum Time to Complete All Tasks	Stack, Greedy, Array +2
2603	Collect Coins in a Tree	Tree, Graph, Topological Sort +1
2608	Shortest Cycle in a Graph	Breadth-First Search, Graph
2612	Minimum Reverse Operations	Breadth-First Search, Union Find, Array +2
2617	Minimum Number of Visited Cells in a Grid	Stack, Breadth-First Search, Union Find +5
2642	Design Graph With Shortest Path Calculator	Graph, Design, Shortest Path +1
2646	Minimize the Total Price of the Trips	Tree, Depth-First Search, Graph +2
2659	Make Array Empty	Greedy, Binary Indexed Tree, Segment Tree +4
2663	Lexicographically Smallest Beautiful String	Greedy, String
2681	Power of Heroes	Array, Math, Dynamic Programming +2
2699	Modify Graph Edge Weights	Graph, Shortest Path, Heap (Priority Queue)
2709	Greatest Common Divisor Traversal	Union Find, Array, Math +1
2713	Maximum Strictly Increasing Cells in a Matrix	Memoization, Array, Hash Table +5
2719	Count of Integers	Math, String, Dynamic Programming
2732	Find a Good Subset of the Matrix	Bit Manipulation, Array, Hash Table +1
2736	Maximum Sum Queries	Stack, Binary Indexed Tree, Segment Tree +4
2742	Painting the Walls	Array, Dynamic Programming
2751	Robot Collisions	Stack, Array, Sorting +1
2763	Sum of Imbalance Numbers of All Subarrays	Array, Hash Table, Enumeration
2781	Length of the Longest Valid Substring	Array, Hash Table, String +1
2790	Maximum Number of Groups With Increasing Length	Greedy, Array, Math +2
2791	Count Paths That Can Form a Palindrome in a Tree	Bit Manipulation, Tree, Depth-First Search +2
2801	Count Stepping Numbers in Range	String, Dynamic Programming
2809	Minimum Time to Make Array Sum At Most x	Array, Dynamic Programming, Sorting
2813	Maximum Elegance of a K-Length Subsequence	Stack, Greedy, Array +3
2818	Apply Operations to Maximize Score	Stack, Greedy, Array +4
2827	Number of Beautiful Integers in the Range	Math, Dynamic Programming
2835	Minimum Operations to Form Subsequence With Target Sum	Greedy, Bit Manipulation, Array
2836	Maximize Value of Function in a Ball Passing Game	Bit Manipulation, Array, Dynamic Programming
2842	Count K-Subsequences of a String With Maximum Beauty	Greedy, Hash Table, Math +2
2846	Minimum Edge Weight Equilibrium Queries in a Tree	Tree, Graph, Array +1
2851	String Transformation	Math, String, Dynamic Programming +1
2858	Minimum Edge Reversals So Every Node Is Reachable	Depth-First Search, Breadth-First Search, Graph +1
2862	Maximum Element-Sum of a Complete Subset of Indices	Array, Math, Number Theory
2867	Count Valid Paths in a Tree	Tree, Depth-First Search, Math +2
2872	Maximum Number of K-Divisible Components	Tree, Depth-First Search
2876	Count Visited Nodes in a Directed Graph	Graph, Memoization, Dynamic Programming
2897	Apply Operations on Array to Maximize Sum of Squares	Greedy, Bit Manipulation, Array +1
2902	Count of Sub-Multisets With Bounded Sum	Array, Hash Table, Dynamic Programming +1
2911	Minimum Changes to Make K Semi-palindromes	Two Pointers, String, Dynamic Programming
2920	Maximum Points After Collecting Coins From All Nodes	Bit Manipulation, Tree, Depth-First Search +3
2926	Maximum Balanced Subsequence Sum	Binary Indexed Tree, Segment Tree, Array +2
2931	Maximum Spending After Buying Items	Greedy, Array, Matrix +2
2935	Maximum Strong Pair XOR II	Bit Manipulation, Trie, Array +2
2940	Find Building Where Alice and Bob Can Meet	Stack, Binary Indexed Tree, Segment Tree +4
2945	Find Maximum Non-decreasing Array Length	Stack, Queue, Array +4
2953	Count Complete Substrings	Hash Table, String, Sliding Window
2954	Count the Number of Infection Sequences	Array, Math, Combinatorics
2959	Number of Possible Sets of Closing Branches	Bit Manipulation, Graph, Enumeration +2
2963	Count the Number of Good Partitions	Array, Hash Table, Math +1
2968	Apply Operations to Maximize Frequency Score	Array, Binary Search, Prefix Sum +2
2972	Count the Number of Incremovable Subarrays II	Array, Two Pointers, Binary Search
2973	Find Number of Coins to Place in Tree Nodes	Tree, Depth-First Search, Dynamic Programming +2
2977	Minimum Cost to Convert String II	Graph, Trie, Array +3
2983	Palindrome Rearrangement Queries	Hash Table, String, Prefix Sum
2999	Count the Number of Powerful Integers	Math, String, Dynamic Programming
0158	Read N Characters Given read4 II - Call Multiple TimesPremium	Array, Interactive, Simulation
0248	Strobogrammatic Number IIIPremium	Recursion, Array, String
0265	Paint House IIPremium	Array, Dynamic Programming
0269	Alien DictionaryPremium	Depth-First Search, Breadth-First Search, Graph +3
0272	Closest Binary Search Tree Value IIPremium	Stack, Tree, Depth-First Search +4
0296	Best Meeting PointPremium	Array, Math, Matrix +1
0302	Smallest Rectangle Enclosing Black PixelsPremium	Depth-First Search, Breadth-First Search, Array +2
0305	Number of Islands IIPremium	Union Find, Array, Hash Table
0317	Shortest Distance from All BuildingsPremium	Breadth-First Search, Array, Matrix
0358	Rearrange String k Distance ApartPremium	Greedy, Hash Table, String +3
0411	Minimum Unique Word AbbreviationPremium	Bit Manipulation, Array, String +1
0425	Word SquaresPremium	Trie, Array, String +1
0428	Serialize and Deserialize N-ary TreePremium	Tree, Depth-First Search, Breadth-First Search +1
0431	Encode N-ary Tree to Binary TreePremium	Tree, Depth-First Search, Breadth-First Search +2
0465	Optimal Account BalancingPremium	Bit Manipulation, Array, Dynamic Programming +2
0471	Encode String with Shortest LengthPremium	String, Dynamic Programming
0489	Robot Room CleanerPremium	Backtracking, Interactive
0499	The Maze IIIPremium	Depth-First Search, Breadth-First Search, Graph +5
0527	Word AbbreviationPremium	Greedy, Trie, Array +2
0548	Split Array with Equal SumPremium	Array, Hash Table, Prefix Sum
0568	Maximum Vacation DaysPremium	Array, Dynamic Programming, Matrix
0569	Median Employee SalaryPremium	Database
0571	Find Median Given Frequency of NumbersPremium	Database
0579	Find Cumulative Salary of an EmployeePremium	Database
0588	Design In-Memory File SystemPremium	Design, Trie, Hash Table +2
0615	Average Salary: Departments VS CompanyPremium	Database
0618	Students Report By GeographyPremium	Database
0631	Design Excel Sum FormulaPremium	Graph, Design, Topological Sort +4
0642	Design Search Autocomplete SystemPremium	Depth-First Search, Design, Trie +4
0644	Maximum Average Subarray IIPremium	Array, Binary Search, Prefix Sum
0656	Coin PathPremium	Array, Dynamic Programming
0660	Remove 9Premium	Math
0683	K Empty SlotsPremium	Binary Indexed Tree, Segment Tree, Queue +5
0711	Number of Distinct Islands IIPremium	Depth-First Search, Breadth-First Search, Union Find +2
0716	Max StackPremium	Stack, Design, Linked List +2
0726	Number of Atoms	Stack, Hash Table, String +1
0727	Minimum Window SubsequencePremium	String, Dynamic Programming, Sliding Window
0759	Employee Free TimePremium	Array, Sorting, Line Sweep +1
0770	Basic Calculator IV	Stack, Recursion, Hash Table +2
0772	Basic Calculator IIIPremium	Stack, Recursion, Math +1
0774	Minimize Max Distance to Gas StationPremium	Array, Binary Search
0843	Guess the Word	Array, Math, String +2
0972	Equal Rational Numbers	Math, String
1063	Number of Valid SubarraysPremium	Stack, Array, Monotonic Stack
1067	Digit Count in RangePremium	Math, Dynamic Programming
1088	Confusing Number IIPremium	Math, Backtracking
1097	Game Play Analysis VPremium	Database
1121	Divide Array Into Increasing SequencesPremium	Array, Counting
1127	User Purchase PlatformPremium	Database
1153	String Transforms Into Another StringPremium	Graph, Hash Table, String
1159	Market Analysis IIPremium	Database
1168	Optimize Water Distribution in a VillagePremium	Union Find, Graph, Minimum Spanning Tree +1
1183	Maximum Number of OnesPremium	Greedy, Math, Sorting +1
1194	Tournament WinnersPremium	Database
1199	Minimum Time to Build BlocksPremium	Greedy, Array, Math +1
1216	Valid Palindrome IIIPremium	String, Dynamic Programming
1225	Report Contiguous DatesPremium	Database
1231	Divide ChocolatePremium	Array, Binary Search
1246	Palindrome RemovalPremium	Array, Dynamic Programming
1259	Handshakes That Don't CrossPremium	Math, Dynamic Programming
1274	Number of Ships in a RectanglePremium	Array, Divide and Conquer, Interactive
1336	Number of Transactions per VisitPremium	Database
1369	Get the Second Most Recent ActivityPremium	Database
1384	Total Sales Amount by YearPremium	Database
1397	Find All Good Strings	String, Dynamic Programming, String Matching
1412	Find the Quiet Students in All ExamsPremium	Database
1416	Restore The Array	String, Dynamic Programming
1479	Sales by Day of the WeekPremium	Database
1516	Move Sub-Tree of N-Ary TreePremium	Tree, Depth-First Search
1520	Maximum Number of Non-Overlapping Substrings	Greedy, String
1548	The Most Similar Path in a GraphPremium	Graph, Dynamic Programming
1591	Strange Printer II	Graph, Topological Sort, Array +1
1597	Build Binary Expression Tree From Infix ExpressionPremium	Stack, Tree, String +1
1635	Hopper Company Queries IPremium	Database
1645	Hopper Company Queries IIPremium	Database
1651	Hopper Company Queries IIIPremium	Database
1692	Count Ways to Distribute CandiesPremium	Dynamic Programming
1714	Sum Of Special Evenly-Spaced Elements In ArrayPremium	Array, Dynamic Programming
1724	Checking Existence of Edge Length Limited Paths IIPremium	Union Find, Graph, Minimum Spanning Tree
1767	Find the Subtasks That Did Not ExecutePremium	Database
1788	Maximize the Beauty of the GardenPremium	Greedy, Array, Hash Table +1
1842	Next Palindrome Using Same DigitsPremium	Two Pointers, String
1892	Page Recommendations IIPremium	Database
1896	Minimum Cost to Change the Final Value of Expression	Stack, Math, String +1
1917	Leetcodify Friends RecommendationsPremium	Database
1919	Leetcodify Similar FriendsPremium	Database
1924	Erect the Fence IIPremium	Geometry, Array, Math
1932	Merge BSTs to Create Single BST	Tree, Depth-First Search, Hash Table +2
1938	Maximum Genetic Difference Query	Bit Manipulation, Depth-First Search, Trie +2
1956	Minimum Time For K Virus Variants to SpreadPremium	Geometry, Array, Math +2
1972	First and Last Call On the Same DayPremium	Database
2004	The Number of Seniors and Juniors to Join the CompanyPremium	Database
2005	Subtree Removal Game with Fibonacci TreePremium	Tree, Math, Dynamic Programming +2
2010	The Number of Seniors and Juniors to Join the Company IIPremium	Database
2030	Smallest K-Length Subsequence With Occurrences of a Letter	Stack, Greedy, String +1

Problems with a complete Python solution are listed first, then by ascending problem number. Or go by technique instead: all LeetCode patterns.