Hard LeetCode Problems in Python with Tests

All 276 Hard LeetCode problems with tested Python solutions. Part 1 of 2: problems 1-200.

Hard holds 276 problems.

#	Problem	Difficulty	Solution
4	Median of Two Sorted Arrays	Hard	solution.py
10	Regular Expression Matching	Hard	solution.py
23	Merge k Sorted Lists	Hard	solution.py
25	Reverse Nodes in k-Group	Hard	solution.py
30	Substring with Concatenation of All Words	Hard	solution.py
32	Longest Valid Parentheses	Hard	solution.py
37	Sudoku Solver	Hard	solution.py
41	First Missing Positive	Hard	solution.py
42	Trapping Rain Water	Hard	solution.py
44	Wildcard Matching	Hard	solution.py
51	N-Queens	Hard	solution.py
52	N-Queens II	Hard	solution.py
60	Permutation Sequence	Hard	solution.py
65	Valid Number	Hard	solution.py
68	Text Justification	Hard	solution.py
72	Edit Distance	Hard	solution.py
76	Minimum Window Substring	Hard	solution.py
84	Largest Rectangle in Histogram	Hard	solution.py
85	Maximal Rectangle	Hard	solution.py
87	Scramble String	Hard	solution.py
115	Distinct Subsequences	Hard	solution.py
123	Best Time to Buy and Sell Stock III	Hard	solution.py
124	Binary Tree Maximum Path Sum	Hard	solution.py
126	Word Ladder II	Hard	solution.py
127	Word Ladder	Hard	solution.py
132	Palindrome Partitioning II	Hard	solution.py
135	Candy	Hard	solution.py
140	Word Break II	Hard	solution.py
149	Max Points on a Line	Hard	solution.py
154	Find Minimum in Rotated Sorted Array II	Hard	solution.py
158	Read N Characters Given read4 II - Call Multiple Times	Hard	solution.py
174	Dungeon Game	Hard	solution.py
188	Best Time to Buy and Sell Stock IV	Hard	solution.py
212	Word Search II	Hard	solution.py
214	Shortest Palindrome	Hard	solution.py
218	The Skyline Problem	Hard	solution.py
220	Contains Duplicate III	Hard	solution.py
224	Basic Calculator	Hard	solution.py
233	Number of Digit One	Hard	solution.py
239	Sliding Window Maximum	Hard	solution.py
248	Strobogrammatic Number III	Hard	solution.py
265	Paint House II	Hard	solution.py
269	Alien Dictionary	Hard	solution.py
272	Closest Binary Search Tree Value II	Hard	solution.py
273	Integer to English Words	Hard	solution.py
282	Expression Add Operators	Hard	solution.py
295	Find Median from Data Stream	Hard	solution.py
296	Best Meeting Point	Hard	solution.py
297	Serialize and Deserialize Binary Tree	Hard	solution.py
301	Remove Invalid Parentheses	Hard	solution.py
302	Smallest Rectangle Enclosing Black Pixels	Hard	solution.py
305	Number of Islands II	Hard	solution.py
312	Burst Balloons	Hard	solution.py
315	Count of Smaller Numbers After Self	Hard	solution.py
317	Shortest Distance from All Buildings	Hard	solution.py
321	Create Maximum Number	Hard	solution.py
327	Count of Range Sum	Hard	solution.py
329	Longest Increasing Path in a Matrix	Hard	solution.py
330	Patching Array	Hard	solution.py
332	Reconstruct Itinerary	Hard	solution.py
335	Self Crossing	Hard	solution.py
336	Palindrome Pairs	Hard	solution.py
352	Data Stream as Disjoint Intervals	Hard	solution.py
354	Russian Doll Envelopes	Hard	solution.py
358	Rearrange String k Distance Apart	Hard	solution.py
363	Max Sum of Rectangle No Larger Than K	Hard	solution.py
381	Insert Delete GetRandom O(1) - Duplicates allowed	Hard	solution.py
391	Perfect Rectangle	Hard	solution.py
403	Frog Jump	Hard	solution.py
407	Trapping Rain Water II	Hard	solution.py
410	Split Array Largest Sum	Hard	solution.py
411	Minimum Unique Word Abbreviation	Hard	solution.py
420	Strong Password Checker	Hard	solution.py
425	Word Squares	Hard	solution.py
428	Serialize and Deserialize N-ary Tree	Hard	solution.py
431	Encode N-ary Tree to Binary Tree	Hard	solution.py
432	All O`one Data Structure	Hard	solution.py
440	K-th Smallest in Lexicographical Order	Hard	solution.py
446	Arithmetic Slices II - Subsequence	Hard	solution.py
458	Poor Pigs	Hard	solution.py
460	LFU Cache	Hard	solution.py
465	Optimal Account Balancing	Hard	solution.py
466	Count The Repetitions	Hard	solution.py
471	Encode String with Shortest Length	Hard	solution.py
472	Concatenated Words	Hard	solution.py
479	Largest Palindrome Product	Hard	solution.py
480	Sliding Window Median	Hard	solution.py
483	Smallest Good Base	Hard	solution.py
488	Zuma Game	Hard	solution.py
489	Robot Room Cleaner	Hard	solution.py
493	Reverse Pairs	Hard	solution.py
499	The Maze III	Hard	solution.py
502	IPO	Hard	solution.py
514	Freedom Trail	Hard	solution.py
517	Super Washing Machines	Hard	solution.py
527	Word Abbreviation	Hard	solution.py
546	Remove Boxes	Hard	solution.py
548	Split Array with Equal Sum	Hard	solution.py
552	Student Attendance Record II	Hard	solution.py
564	Find the Closest Palindrome	Hard	solution.py
568	Maximum Vacation Days	Hard	solution.py
587	Erect the Fence	Hard	solution.py
588	Design In-Memory File System	Hard	solution.py
591	Tag Validator	Hard	solution.py
600	Non-negative Integers without Consecutive Ones	Hard	solution.py
629	K Inverse Pairs Array	Hard	solution.py
630	Course Schedule III	Hard	solution.py
631	Design Excel Sum Formula	Hard	solution.py
632	Smallest Range Covering Elements from K Lists	Hard	solution.py
639	Decode Ways II	Hard	solution.py
642	Design Search Autocomplete System	Hard	solution.py
644	Maximum Average Subarray II	Hard	solution.py
656	Coin Path	Hard	solution.py
660	Remove 9	Hard	solution.py
664	Strange Printer	Hard	solution.py
668	Kth Smallest Number in Multiplication Table	Hard	solution.py
675	Cut Off Trees for Golf Event	Hard	solution.py
679	24 Game	Hard	solution.py
683	K Empty Slots	Hard	solution.py
685	Redundant Connection II	Hard	solution.py
689	Maximum Sum of 3 Non-Overlapping Subarrays	Hard	solution.py
691	Stickers to Spell Word	Hard	solution.py
699	Falling Squares	Hard	solution.py
710	Random Pick with Blacklist	Hard	solution.py
711	Number of Distinct Islands II	Hard	solution.py
715	Range Module	Hard	solution.py
716	Max Stack	Hard	solution.py
719	Find K-th Smallest Pair Distance	Hard	solution.py
726	Number of Atoms	Hard	solution.py
727	Minimum Window Subsequence	Hard	solution.py
730	Count Different Palindromic Subsequences	Hard	solution.py
732	My Calendar III	Hard	solution.py
736	Parse Lisp Expression	Hard	solution.py
741	Cherry Pickup	Hard	solution.py
745	Prefix and Suffix Search	Hard	solution.py
749	Contain Virus	Hard	solution.py
753	Cracking the Safe	Hard	solution.py
757	Set Intersection Size At Least Two	Hard	solution.py
759	Employee Free Time	Hard	solution.py
761	Special Binary String	Hard	solution.py
765	Couples Holding Hands	Hard	solution.py
768	Max Chunks To Make Sorted II	Hard	solution.py
770	Basic Calculator IV	Hard	solution.py
772	Basic Calculator III	Hard	solution.py
773	Sliding Puzzle	Hard	solution.py
774	Minimize Max Distance to Gas Station	Hard	solution.py
778	Swim in Rising Water	Hard	solution.py
780	Reaching Points	Hard	solution.py
782	Transform to Chessboard	Hard	solution.py
793	Preimage Size of Factorial Zeroes Function	Hard	solution.py
798	Smallest Rotation with Highest Score	Hard	solution.py
801	Minimum Swaps To Make Sequences Increasing	Hard	solution.py
803	Bricks Falling When Hit	Hard	solution.py
805	Split Array With Same Average	Hard	solution.py
810	Chalkboard XOR Game	Hard	solution.py
815	Bus Routes	Hard	solution.py
818	Race Car	Hard	solution.py
827	Making A Large Island	Hard	solution.py
828	Count Unique Characters of All Substrings of a Given String	Hard	solution.py
829	Consecutive Numbers Sum	Hard	solution.py
834	Sum of Distances in Tree	Hard	solution.py
839	Similar String Groups	Hard	solution.py
843	Guess the Word	Hard	solution.py
847	Shortest Path Visiting All Nodes	Hard	solution.py
850	Rectangle Area II	Hard	solution.py
854	K-Similar Strings	Hard	solution.py
857	Minimum Cost to Hire K Workers	Hard	solution.py
862	Shortest Subarray with Sum at Least K	Hard	solution.py
864	Shortest Path to Get All Keys	Hard	solution.py
871	Minimum Number of Refueling Stops	Hard	solution.py
878	Nth Magical Number	Hard	solution.py
879	Profitable Schemes	Hard	solution.py
882	Reachable Nodes In Subdivided Graph	Hard	solution.py
887	Super Egg Drop	Hard	solution.py
891	Sum of Subsequence Widths	Hard	solution.py
895	Maximum Frequency Stack	Hard	solution.py
899	Orderly Queue	Hard	solution.py
902	Numbers At Most N Given Digit Set	Hard	solution.py
903	Valid Permutations for DI Sequence	Hard	solution.py
906	Super Palindromes	Hard	solution.py
913	Cat and Mouse	Hard	solution.py
920	Number of Music Playlists	Hard	solution.py
924	Minimize Malware Spread	Hard	solution.py
927	Three Equal Parts	Hard	solution.py
928	Minimize Malware Spread II	Hard	solution.py
936	Stamping The Sequence	Hard	solution.py
940	Distinct Subsequences II	Hard	solution.py
943	Find the Shortest Superstring	Hard	solution.py
952	Largest Component Size by Common Factor	Hard	solution.py
956	Tallest Billboard	Hard	solution.py
960	Delete Columns to Make Sorted III	Hard	solution.py
964	Least Operators to Express Number	Hard	solution.py
968	Binary Tree Cameras	Hard	solution.py
972	Equal Rational Numbers	Hard	solution.py
975	Odd Even Jump	Hard	solution.py
980	Unique Paths III	Hard	solution.py
982	Triples with Bitwise AND Equal To Zero	Hard	solution.py
987	Vertical Order Traversal of a Binary Tree	Hard	solution.py
992	Subarrays with K Different Integers	Hard	solution.py
995	Minimum Number of K Consecutive Bit Flips	Hard	solution.py

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