leetcode hard

#	Title	Solution	Acceptance	Difficulty	Frequency
	4	Median of Two Sorted Arrays		27.2%	Hard
	10	Regular Expression Matching		25.6%	Hard
	23	Merge k Sorted Lists		35.8%	Hard
	25	Reverse Nodes in k-Group		37.7%	Hard
	30	Substring with Concatenation of All Words		24.1%	Hard
	32	Longest Valid Parentheses		26.2%	Hard
	37	Sudoku Solver		38.5%	Hard
	41	First Missing Positive		29.6%	Hard
	42	Trapping Rain Water		44.4%	Hard
	44	Wildcard Matching		23.3%	Hard
	45	Jump Game II		28.7%	Hard
	51	N-Queens		41.1%	Hard
	52	N-Queens II		53.4%	Hard
	57	Insert Interval		31.7%	Hard
	65	Valid Number		14.3%	Hard
	68	Text Justification		24.2%	Hard
	72	Edit Distance		39.1%	Hard
	76	Minimum Window Substring		31.7%	Hard
	84	Largest Rectangle in Histogram		32.1%	Hard
	85	Maximal Rectangle		34.4%	Hard
	87	Scramble String		32.1%	Hard
	97	Interleaving String		28.7%	Hard
	99	Recover Binary Search Tree		35.5%	Hard
	115	Distinct Subsequences		35.7%	Hard
	123	Best Time to Buy and Sell Stock III		34.6%	Hard
	124	Binary Tree Maximum Path Sum		30.8%	Hard
	126	Word Ladder II		18.7%	Hard
	128	Longest Consecutive Sequence		42.5%	Hard
	132	Palindrome Partitioning II		28.2%	Hard
	135	Candy		29.1%	Hard
	140	Word Break II		28.1%	Hard
	145	Binary Tree Postorder Traversal		49.9%	Hard
	149	Max Points on a Line		16.0%	Hard
	154	Find Minimum in Rotated Sorted Array II		39.7%	Hard
	158	Read N Characters Given Read4 II - Call multiple times		27.6%	Hard
	159	Longest Substring with At Most Two Distinct Characters		47.7%	Hard
	164	Maximum Gap		33.2%	Hard
	174	Dungeon Game		27.8%	Hard
	185	Department Top Three Salaries		27.8%	Hard
	188	Best Time to Buy and Sell Stock IV		26.8%	Hard
	212	Word Search II		29.8%	Hard
	214	Shortest Palindrome		28.1%	Hard
	218	The Skyline Problem		32.3%	Hard
	224	Basic Calculator		33.7%	Hard
	233	Number of Digit One		30.6%	Hard
	239	Sliding Window Maximum		39.1%	Hard
	248	Strobogrammatic Number III		37.3%	Hard
	262	Trips and Users		26.4%	Hard
	265	Paint House II		42.2%	Hard
	269	Alien Dictionary		32.0%	Hard
	272	Closest Binary Search Tree Value II		46.3%	Hard
	273	Integer to English Words		24.8%	Hard
	282	Expression Add Operators		33.4%	Hard
	291	Word Pattern II		41.6%	Hard
	295	Find Median from Data Stream		38.2%	Hard
	296	Best Meeting Point		55.8%	Hard
	297	Serialize and Deserialize Binary Tree		42.3%	Hard
	301	Remove Invalid Parentheses		40.1%	Hard
	302	Smallest Rectangle Enclosing Black Pixels		49.8%	Hard
	305	Number of Islands II		41.3%	Hard
	308	Range Sum Query 2D - Mutable		32.9%	Hard
	312	Burst Balloons		48.3%	Hard
	315	Count of Smaller Numbers After Self		39.0%	Hard
	316	Remove Duplicate Letters		33.3%	Hard
	317	Shortest Distance from All Buildings		38.8%	Hard
	321	Create Maximum Number		25.8%	Hard
	327	Count of Range Sum		33.4%	Hard
	329	Longest Increasing Path in a Matrix		40.8%	Hard
	330	Patching Array		33.6%	Hard
	335	Self Crossing		27.2%	Hard
	336	Palindrome Pairs		31.7%	Hard
	340	Longest Substring with At Most K Distinct Characters		40.8%	Hard
	352	Data Stream as Disjoint Intervals		44.2%	Hard
	354	Russian Doll Envelopes		34.3%	Hard
	358	Rearrange String k Distance Apart		33.4%	Hard
	363	Max Sum of Rectangle No Larger Than K		35.6%	Hard
	381	Insert Delete GetRandom O(1) - Duplicates allowed		32.5%	Hard
	391	Perfect Rectangle		28.6%	Hard
	403	Frog Jump		36.9%	Hard
	407	Trapping Rain Water II		39.9%	Hard
	410	Split Array Largest Sum		42.8%	Hard
	411	Minimum Unique Word Abbreviation		35.2%	Hard
	420	Strong Password Checker		16.6%	Hard
	425	Word Squares		45.2%	Hard
	428	Serialize and Deserialize N-ary Tree		55.2%	Hard
	431	Encode N-ary Tree to Binary Tree		65.0%	Hard
	432	All O`one Data Structure		30.3%	Hard
	440	K-th Smallest in Lexicographical Order		27.0%	Hard
	446	Arithmetic Slices II - Subsequence		30.9%	Hard
	458	Poor Pigs		46.1%	Hard
	460	LFU Cache		29.7%	Hard
	465	Optimal Account Balancing		43.6%	Hard
	466	Count The Repetitions		27.4%	Hard
	471	Encode String with Shortest Length		45.6%	Hard
	472	Concatenated Words		36.4%	Hard
	479	Largest Palindrome Product		27.8%	Hard
	480	Sliding Window Median		33.6%	Hard
	483	Smallest Good Base		34.3%	Hard
	488	Zuma Game		39.7%	Hard
	489	Robot Room Cleaner		65.8%	Hard
	493	Reverse Pairs		23.5%	Hard
	499	The Maze III		38.0%	Hard
	502	IPO		38.4%	Hard
	514	Freedom Trail		41.0%	Hard
	517	Super Washing Machines		37.0%	Hard
	527	Word Abbreviation		51.2%	Hard
	546	Remove Boxes		38.9%	Hard
	552	Student Attendance Record II		33.8%	Hard
	564	Find the Closest Palindrome		19.0%	Hard
	568	Maximum Vacation Days		38.5%	Hard
	569	Median Employee Salary		49.6%	Hard
	571	Find Median Given Frequency of Numbers		46.5%	Hard
	579	Find Cumulative Salary of an Employee		34.7%	Hard
	587	Erect the Fence		34.6%	Hard
	588	Design In-Memory File System		41.3%	Hard
	591	Tag Validator		33.2%	Hard
	600	Non-negative Integers without Consecutive Ones		33.1%	Hard
	601	Human Traffic of Stadium		37.3%	Hard
	615	Average Salary: Departments VS Company		39.2%	Hard
	618	Students Report By Geography		44.3%	Hard
	629	K Inverse Pairs Array		29.6%	Hard
	630	Course Schedule III		32.4%	Hard
	631	Design Excel Sum Formula		29.5%	Hard
	632	Smallest Range Covering Elements from K Lists		48.8%	Hard
	639	Decode Ways II		25.5%	Hard
	642	Design Search Autocomplete System		39.3%	Hard
	644	Maximum Average Subarray II		29.5%	Hard
	656	Coin Path		27.5%	Hard
	660	Remove 9		52.4%	Hard
	664	Strange Printer		37.3%	Hard
	668	Kth Smallest Number in Multiplication Table		42.8%	Hard
	675	Cut Off Trees for Golf Event		31.6%	Hard
	679	24 Game		43.6%	Hard
	683	K Empty Slots		34.5%	Hard
	685	Redundant Connection II		31.1%	Hard
	689	Maximum Sum of 3 Non-Overlapping Subarrays		44.3%	Hard
	691	Stickers to Spell Word		39.1%	Hard
	699	Falling Squares		40.5%	Hard
	710	Random Pick with Blacklist		32.0%	Hard
	711	Number of Distinct Islands II		47.0%	Hard
	715	Range Module		36.2%	Hard
	719	Find K-th Smallest Pair Distance		29.8%	Hard
	726	Number of Atoms		45.5%	Hard
	727	Minimum Window Subsequence		38.2%	Hard
	730	Count Different Palindromic Subsequences		39.7%	Hard
	732	My Calendar III		56.6%	Hard
	736	Parse Lisp Expression		45.1%	Hard
	741	Cherry Pickup		30.7%	Hard
	745	Prefix and Suffix Search		31.5%	Hard
	749	Contain Virus		41.5%	Hard
	753	Cracking the Safe		47.6%	Hard
	757	Set Intersection Size At Least Two		36.9%	Hard
	759	Employee Free Time		62.4%	Hard
	761	Special Binary String		52.4%	Hard
	765	Couples Holding Hands		52.1%	Hard
	768	Max Chunks To Make Sorted II		46.6%	Hard
	770	Basic Calculator IV		45.5%	Hard
	772	Basic Calculator III		41.9%	Hard
	773	Sliding Puzzle		53.9%	Hard
	774	Minimize Max Distance to Gas Station		43.0%	Hard
	778	Swim in Rising Water		48.7%	Hard
	780	Reaching Points		27.7%	Hard
	782	Transform to Chessboard		39.5%	Hard
	786	K-th Smallest Prime Fraction		40.5%	Hard
	793	Preimage Size of Factorial Zeroes Function		39.2%	Hard
	798	Smallest Rotation with Highest Score		41.1%	Hard
	803	Bricks Falling When Hit		29.1%	Hard
	805	Split Array With Same Average		24.8%	Hard
	810	Chalkboard XOR Game		45.0%	Hard
	815	Bus Routes		40.6%	Hard
	818	Race Car		36.0%	Hard
	827	Making A Large Island		43.6%	Hard
	828	Unique Letter String		41.0%	Hard
	829	Consecutive Numbers Sum		34.1%	Hard
	834	Sum of Distances in Tree		40.6%	Hard
	839	Similar String Groups		35.4%	Hard
	843	Guess the Word		44.5%	Hard
	847	Shortest Path Visiting All Nodes		48.0%	Hard
	850	Rectangle Area II		45.4%	Hard
	854	K-Similar Strings		34.7%	Hard
	857	Minimum Cost to Hire K Workers		48.2%	Hard
	862	Shortest Subarray with Sum at Least K		22.6%	Hard
	864	Shortest Path to Get All Keys		37.3%	Hard
	871	Minimum Number of Refueling Stops		29.9%	Hard
	878	Nth Magical Number		25.9%	Hard
	879	Profitable Schemes		37.3%	Hard
	882	Reachable Nodes In Subdivided Graph		38.7%	Hard
	887	Super Egg Drop		25.1%	Hard
	891	Sum of Subsequence Widths		29.7%	Hard
	895	Maximum Frequency Stack		57.1%	Hard
	899	Orderly Queue		48.1%	Hard
	902	Numbers At Most N Given Digit Set		29.0%	Hard
	903	Valid Permutations for DI Sequence		45.4%	Hard
	906	Super Palindromes		30.6%	Hard
	913	Cat and Mouse		29.1%	Hard
	920	Number of Music Playlists		43.9%	Hard
	924	Minimize Malware Spread		40.7%	Hard
	927	Three Equal Parts		30.8%	Hard
	928	Minimize Malware Spread II		39.4%	Hard
	936	Stamping The Sequence		35.5%	Hard
	940	Distinct Subsequences II		40.3%	Hard
	943	Find the Shortest Superstring		39.1%	Hard
	952	Largest Component Size by Common Factor		26.9%	Hard
	956	Tallest Billboard		38.5%	Hard
	960	Delete Columns to Make Sorted III		52.8%	Hard
	964	Least Operators to Express Number		40.6%	Hard
	968	Binary Tree Cameras		35.8%	Hard
	972	Equal Rational Numbers		39.9%	Hard
	975	Odd Even Jump		46.0%	Hard
	980	Unique Paths III		71.3%	Hard
	982	Triples with Bitwise AND Equal To Zero		54.5%	Hard
	992	Subarrays with K Different Integers		45.1%	Hard
	995	Minimum Number of K Consecutive Bit Flips		47.6%	Hard
	996	Number of Squareful Arrays		47.7%	Hard
	1000	Minimum Cost to Merge Stones		34.8%	Hard
	1001	Grid Illumination		34.8%	Hard
	1012	Numbers With Repeated Digits		34.9%	Hard
	1028	Recover a Tree From Preorder Traversal		69.4%	Hard
	1032	Stream of Characters		42.9%	Hard
	1036	Escape a Large Maze		35.0%	Hard
	1044	Longest Duplicate Substring		22.9%	Hard
	1063	Number of Valid Subarrays		72.8%	Hard
	1067	Digit Count in Range		37.9%	Hard
	1074	Number of Submatrices That Sum to Target		57.9%	Hard
	1088	Confusing Number II		36.1%	Hard
	1092	Shortest Common Supersequence		48.3%	Hard
	1095	Find in Mountain Array		34.3%	Hard
	1096	Brace Expansion II		56.7%	Hard
	1097	Game Play Analysis V		47.0%	Hard
	1106	Parsing A Boolean Expression		57.7%	Hard
	1121	Divide Array Into Increasing Sequences		53.6%	Hard
	1125	Smallest Sufficient Team		44.5%	Hard
	1127	User Purchase Platform		45.4%	Hard
	1136	Parallel Courses		60.1%	Hard
	1147	Longest Chunked Palindrome Decomposition		57.8%	Hard
	1153	String Transforms Into Another String		28.7%	Hard
	1157	Online Majority Element In Subarray		32.3%	Hard
	1159	Market Analysis II		48.8%	Hard
	1163	Last Substring in Lexicographical Order		29.9%	Hard
	1168	Optimize Water Distribution in a Village		48.9%	Hard
	1172	Dinner Plate Stacks		42.1%	Hard
	1178	Number of Valid Words for Each Puzzle		23.7%	Hard