Hard LeetCode Problems: Page 4 of 4

Problems 601 to 661 of the 661 Hard-rated problems in this library, continuing the list on the Hard hub.

Page 4 of 4

Hard problems, page 4
No.	Problem	Topics
2097	Valid Arrangement of Pairs	Depth-First Search, Graph, Eulerian Circuit
2118	Build the EquationPremium	Database
2123	Minimum Operations to Remove Adjacent Ones in MatrixPremium	Graph, Array, Matrix
2143	Choose Numbers From Two Arrays in RangePremium	Array, Dynamic Programming
2153	The Number of Passengers in Each Bus IIPremium	Database
2158	Amount of New Area Painted Each DayPremium	Segment Tree, Array, Ordered Set
2173	Longest Winning StreakPremium	Database
2183	Count Array Pairs Divisible by K	Array, Math, Number Theory
2199	Finding the Topic of Each PostPremium	Database
2204	Distance to a Cycle in Undirected GraphPremium	Depth-First Search, Breadth-First Search, Union Find +1
2223	Sum of Scores of Built Strings	String, Binary Search, String Matching +3
2247	Maximum Cost of Trip With K HighwaysPremium	Bit Manipulation, Graph, Dynamic Programming +1
2252	Dynamic Pivoting of a TablePremium	Database
2253	Dynamic Unpivoting of a TablePremium	Database
2254	Design Video Sharing PlatformPremium	Stack, Design, Hash Table +1
2263	Make Array Non-decreasing or Non-increasingPremium	Greedy, Dynamic Programming
2277	Closest Node to Path in TreePremium	Tree, Depth-First Search, Breadth-First Search +1
2307	Check for Contradictions in EquationsPremium	Depth-First Search, Union Find, Graph +1
2313	Minimum Flips in Binary Tree to Get ResultPremium	Tree, Depth-First Search, Dynamic Programming +1
2355	Maximum Number of Books You Can TakePremium	Stack, Array, Dynamic Programming +1
2361	Minimum Costs Using the Train LinePremium	Array, Dynamic Programming
2362	Generate the InvoicePremium	Database
2371	Minimize Maximum Value in a GridPremium	Union Find, Graph, Topological Sort +3
2403	Minimum Time to Kill All MonstersPremium	Bit Manipulation, Array, Dynamic Programming +1
2459	Sort Array by Moving Items to Empty SpacePremium	Greedy, Array, Sorting
2474	Customers With Strictly Increasing PurchasesPremium	Database
2479	Maximum XOR of Two Non-Overlapping SubtreesPremium	Tree, Depth-First Search, Graph +1
2494	Merge Overlapping Events in the Same HallPremium	Database
2519	Count the Number of K-Big IndicesPremium	Binary Indexed Tree, Segment Tree, Array +4
2524	Maximum Frequency Score of a SubarrayPremium	Stack, Array, Hash Table +2
2534	Time Taken to Cross the DoorPremium	Queue, Array, Simulation
2604	Minimum Time to Eat All GrainsPremium	Array, Two Pointers, Binary Search +1
2613	Beautiful PairsPremium	Geometry, Array, Math +3
2630	Memoize II	JavaScript
2647	Color the Triangle RedPremium	Array, Math
2650	Design Cancellable Function	JavaScript
2675	Array of Objects to MatrixPremium	JavaScript
2691	Immutability HelperPremium	JavaScript
2701	Consecutive Transactions with Increasing AmountsPremium	Database
2702	Minimum Operations to Make Numbers Non-positivePremium	Array, Binary Search
2714	Find Shortest Path with K HopsPremium	Graph, Shortest Path, Heap (Priority Queue)
2720	Popularity PercentagePremium	Database
2752	Customers with Maximum Number of Transactions on Consecutive DaysPremium	Database
2753	Count Houses in a Circular Street IIPremium	General
2756	Query BatchingPremium	JavaScript
2759	Convert JSON String to ObjectPremium	JavaScript
2792	Count Nodes That Are Great EnoughPremium	Tree, Depth-First Search, Divide and Conquer +1
2793	Status of Flight TicketsPremium	Database
2814	Minimum Time Takes to Reach Destination Without DrowningPremium	Breadth-First Search, Array, Matrix
2819	Minimum Relative Loss After Buying ChocolatesPremium	Array, Binary Search, Prefix Sum +1
2868	The Wording GamePremium	Greedy, Array, Math +3
2912	Number of Ways to Reach Destination in the GridPremium	Math, Dynamic Programming, Combinatorics
2916	Subarrays Distinct Element Sum of Squares II	Binary Indexed Tree, Segment Tree, Array +1
2921	Maximum Profitable Triplets With Increasing Prices IIPremium	Binary Indexed Tree, Segment Tree, Array
2927	Distribute Candies Among Children IIIPremium	Math, Combinatorics
2941	Maximum GCD-Sum of a SubarrayPremium	Array, Math, Binary Search +1
2949	Count Beautiful Substrings II	Hash Table, Math, String +2
2969	Minimum Number of Coins for Fruits IIPremium	Queue, Array, Dynamic Programming +2
2991	Top Three WineriesPremium	Database
2994	Friday Purchases IIPremium	Database
2995	Viewers Turned StreamersPremium	Database

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