LeetCode Solutions

Introduction

LeetCode is a very good website to sharpen your programming/problem-solving skills. Of course, not all solutions here are optimal and your suggestions and contributions are welcomed.

Contents

#	Title	Solution	Difficulty
1	Two Sum	Java,Python
2	Add Two Numbers	Java,Python
3	Longest Substring Without Repeating Characters	Java,Python
4	Median of Two Sorted Arrays	Python
5	Longest Palindromic Substring	Python
6	Zigzag Conversion	Python
7	Reverse Integer	Java
8	String to Integer (atoi)	Python
9	Palindrome Number	Java
10	Regular Expression Matching	Python
11	Container With Most Water	Java,Python
12	Integer to Roman	Java
13	Roman to Integer	Java
14	Longest Common Prefix	Java
15	3Sum	Java,Python
16	3Sum Closest	Java
17	Letter Combinations of a Phone Number	Java
18	4Sum	Python
19	Remove Nth Node From End of List	Java
20	Valid Parentheses	Java
21	Merge Two Sorted Lists	Java,Python
22	Generate Parentheses	Java
23	Merge k Sorted Lists	Python
24	Swap Nodes in Pairs	Java
25	Reverse Nodes in k-Group	Python
26	Remove Duplicates from Sorted Array	Java
27	Remove Element	Java
28	Find the Index of the First Occurrence in a String	Python
29	Divide Two Integers	Python
31	Next Permutation	Python
32	Longest Valid Parentheses	Python
33	Search in Rotated Sorted Array	Java,Python
34	Find First and Last Position of Element in Sorted Array	Python
35	Search Insert Position	Java,Python
36	Valid Sudoku	Java
37	Sudoku Solver	Python
38	Count and Say	Java
39	Combination Sum	Java,Python
40	Combination Sum II	Python
41	First Missing Positive	Python
42	Trapping Rain Water	Python
43	Multiply Strings	Java
44	Wildcard Matching	Java
45	Jump Game II	Python
46	Permutations	Java,Python
47	Permutations II	Python
48	Rotate Image	Python
49	Group Anagrams	Python
50	Pow(x, n)	Python
51	N-Queens	Python
52	N-Queens II	Python
53	Maximum Subarray	Java,Python
54	Spiral Matrix	Java,Python
55	Jump Game	Java
56	Merge Intervals	Python
57	Insert Interval	Python
58	Length of Last Word	Java
59	Spiral Matrix II	Python
60	Permutation Sequence	Python
61	Rotate List	Java,Python
62	Unique Paths	Python
63	Unique Paths II	Python
64	Minimum Path Sum	Python
65	Valid Number	Python
66	Plus One	Java
67	Add Binary	Java
69	Sqrt(x)	C++,Python
70	Climbing Stairs	Java
71	Simplify Path	Python
72	Edit Distance	Java,C++
73	Set Matrix Zeroes	Java
74	Search a 2D Matrix	Java
75	Sort Colors	Java,Python
76	Minimum Window Substring	Python
77	Combinations	Java,Python
78	Subsets	Python
79	Word Search	Python
80	Remove Duplicates from Sorted Array II	Java
81	Search in Rotated Sorted Array II	Python
82	Remove Duplicates from Sorted List II	Java,C++,Python
83	Remove Duplicates from Sorted List	Java,Python
84	Largest Rectangle in Histogram	Python
85	Maximal Rectangle	Python
86	Partition List	Python
88	Merge Sorted Array	Java
89	Gray Code	Python
90	Subsets II	Python
91	Decode Ways	Python
92	Reverse Linked List II	Java
93	Restore IP Addresses	Python
94	Binary Tree Inorder Traversal	Python
95	Unique Binary Search Trees II	Python
96	Unique Binary Search Trees	Python
97	Interleaving String	Python
98	Validate Binary Search Tree	Java
100	Same Tree	Java
101	Symmetric Tree	Java
102	Binary Tree Level Order Traversal	Java,Python
103	Binary Tree Zigzag Level Order Traversal	Python
104	Maximum Depth of Binary Tree	Java,Python
105	Construct Binary Tree from Preorder and Inorder Traversal	Python
106	Construct Binary Tree from Inorder and Postorder Traversal	Python
107	Binary Tree Level Order Traversal II	Java
108	Convert Sorted Array to Binary Search Tree	Python
109	Convert Sorted List to Binary Search Tree	Python
110	Balanced Binary Tree	Java
111	Minimum Depth of Binary Tree	Java
112	Path Sum	Java,Python
113	Path Sum II	Java,Python
114	Flatten Binary Tree to Linked List	Python
116	Populating Next Right Pointers in Each Node	Python
117	Populating Next Right Pointers in Each Node II	Python
118	Pascal's Triangle	Java
119	Pascal's Triangle II	Java
120	Triangle	Python
121	Best Time to Buy and Sell Stock	Python
122	Best Time to Buy and Sell Stock II	Python
123	Best Time to Buy and Sell Stock III	Python
124	Binary Tree Maximum Path Sum	Python
125	Valid Palindrome	Java
126	Word Ladder II	Python
127	Word Ladder	Java,Python
128	Longest Consecutive Sequence	Python
129	Sum Root to Leaf Numbers	Java
130	Surrounded Regions	Python
131	Palindrome Partitioning	Python
132	Palindrome Partitioning II	Python
133	Clone Graph	Python
134	Gas Station	Python
135	Candy	Python
136	Single Number	Java
137	Single Number II	Java
138	Copy List with Random Pointer	Java
139	Word Break	Java
140	Word Break II	Python
141	Linked List Cycle	Java
142	Linked List Cycle II	Java
143	Reorder List	Python
144	Binary Tree Preorder Traversal	Python
145	Binary Tree Postorder Traversal	Python
146	LRU Cache	Python
147	Insertion Sort List	Python
148	Sort List	Python
149	Max Points on a Line	Java
150	Evaluate Reverse Polish Notation	Python
151	Reverse Words in a String	Python
152	Maximum Product Subarray	Python
153	Find Minimum in Rotated Sorted Array	Python
155	Min Stack	Java,Python
157	Read N Characters Given Read4	Python
158	Read N Characters Given read4 II - Call Multiple Times	Python
159	Longest Substring with At Most Two Distinct Characters	Python
160	Intersection of Two Linked Lists	Java,Python
161	One Edit Distance	Python
162	Find Peak Element	Java,Python
163	Missing Ranges	Python
164	Maximum Gap	Python
165	Compare Version Numbers	Java,Python
166	Fraction to Recurring Decimal	Python
167	Two Sum II - Input Array Is Sorted	Python
168	Excel Sheet Column Title	Python
169	Majority Element	Java,Python
171	Excel Sheet Column Number	Python
172	Factorial Trailing Zeroes	Python
173	Binary Search Tree Iterator	Python
174	Dungeon Game	Python
175	Combine Two Tables	SQL
176	Second Highest Salary	SQL
177	Nth Highest Salary	SQL
178	Rank Scores	SQL
179	Largest Number	Python
180	Consecutive Numbers	SQL
181	Employees Earning More Than Their Managers	SQL
182	Duplicate Emails	SQL
183	Customers Who Never Order	SQL
184	Department Highest Salary	SQL
185	Department Top Three Salaries	SQL
187	Repeated DNA Sequences	Java,Python
188	Best Time to Buy and Sell Stock IV	Python
189	Rotate Array	Java,Python
190	Reverse Bits	Java,Python
191	Number of 1 Bits	Java,Python
192	Word Frequency	Shell
193	Valid Phone Numbers	Shell
194	Transpose File	Shell
195	Tenth Line	Shell
196	Delete Duplicate Emails	SQL
197	Rising Temperature	SQL
198	House Robber	Java,Python
199	Binary Tree Right Side View	Python
200	Number of Islands	Python
201	Bitwise AND of Numbers Range	Python
202	Happy Number	Java
203	Remove Linked List Elements	Java,Python
204	Count Primes	Python
205	Isomorphic Strings	Java,Python
206	Reverse Linked List	Java,Python
207	Course Schedule	Python
208	Implement Trie (Prefix Tree)	Python
209	Minimum Size Subarray Sum	Python
210	Course Schedule II	Python
211	Design Add and Search Words Data Structure	Python
212	Word Search II	Python
213	House Robber II	Python
215	Kth Largest Element in an Array	Python
216	Combination Sum III	Python
217	Contains Duplicate	Java,Python
218	The Skyline Problem	Python
219	Contains Duplicate II	Java,Python
220	Contains Duplicate III	Python
221	Maximal Square	Python
222	Count Complete Tree Nodes	Python
223	Rectangle Area	Python
224	Basic Calculator	Python
225	Implement Stack using Queues	Python
226	Invert Binary Tree	Java,Python
227	Basic Calculator II	Python
228	Summary Ranges	Java,Python
229	Majority Element II	Java,Python
230	Kth Smallest Element in a BST	Python
231	Power of Two	Python
232	Implement Queue using Stacks	Python
233	Number of Digit One	C++,Python
234	Palindrome Linked List	Java,Python
235	Lowest Common Ancestor of a Binary Search Tree	Java,Python
236	Lowest Common Ancestor of a Binary Tree	Python
237	Delete Node in a Linked List	C++,Python
238	Product of Array Except Self	Python
239	Sliding Window Maximum	Python
240	Search a 2D Matrix II	Python
241	Different Ways to Add Parentheses	Python
242	Valid Anagram	Java
246	Strobogrammatic Number	Python
247	Strobogrammatic Number II	Python
249	Group Shifted Strings	Python
251	Flatten 2D Vector	Python
252	Meeting Rooms	Python
253	Meeting Rooms II	Python
257	Binary Tree Paths	Java
258	Add Digits	C++
260	Single Number III	Java
262	Trips and Users	SQL
263	Ugly Number	Java
264	Ugly Number II	Java
268	Missing Number	Java
269	Alien Dictionary	Python
270	Closest Binary Search Tree Value	Python
271	Encode and Decode Strings	Python
273	Integer to English Words	Java
274	H-Index	Java
275	H-Index II	Python
277	Find the Celebrity	Python
278	First Bad Version	Python
279	Perfect Squares	Java
282	Expression Add Operators	Python
283	Move Zeroes	C++
284	Peeking Iterator	Java
285	Inorder Successor in BST	Python
286	Walls and Gates	Python
287	Find the Duplicate Number	Java,Python
289	Game of Life	Python
290	Word Pattern	Java
292	Nim Game	Java,C++
295	Find Median from Data Stream	Java
297	Serialize and Deserialize Binary Tree	Python
299	Bulls and Cows	Java
300	Longest Increasing Subsequence	Java
301	Remove Invalid Parentheses	Python
303	Range Sum Query - Immutable	Java
304	Range Sum Query 2D - Immutable	Java
307	Range Sum Query - Mutable	Python
308	Range Sum Query 2D - Mutable	Python
309	Best Time to Buy and Sell Stock with Cooldown	Python
310	Minimum Height Trees	Python
311	Sparse Matrix Multiplication	Python
312	Burst Balloons	Python
313	Super Ugly Number	Python
314	Binary Tree Vertical Order Traversal	Python
315	Count of Smaller Numbers After Self	Python
316	Remove Duplicate Letters	Python
317	Shortest Distance from All Buildings	Python
318	Maximum Product of Word Lengths	Python
319	Bulb Switcher	Python
322	Coin Change	Python
323	Number of Connected Components in an Undirected Graph	Python
324	Wiggle Sort II	Python
325	Maximum Size Subarray Sum Equals k	Python
326	Power of Three	Python
328	Odd Even Linked List	Java
329	Longest Increasing Path in a Matrix	Python
330	Patching Array	Java
331	Verify Preorder Serialization of a Binary Tree	Python
332	Reconstruct Itinerary	Python
334	Increasing Triplet Subsequence	Python
336	Palindrome Pairs	Python
337	House Robber III	Python
338	Counting Bits	Java
340	Longest Substring with At Most K Distinct Characters	Python
341	Flatten Nested List Iterator	Python
342	Power of Four	Python
343	Integer Break	Python
344	Reverse String	Java
345	Reverse Vowels of a String	Python
347	Top K Frequent Elements	Python
348	Design Tic-Tac-Toe	Python
349	Intersection of Two Arrays	Python
350	Intersection of Two Arrays II	Python
351	Android Unlock Patterns	Python
353	Design Snake Game	Python
354	Russian Doll Envelopes	Python
355	Design Twitter	Python
357	Count Numbers with Unique Digits	Python
359	Logger Rate Limiter	Python
367	Valid Perfect Square	C++
368	Largest Divisible Subset	Python
371	Sum of Two Integers	Java
374	Guess Number Higher or Lower	Python
376	Wiggle Subsequence	Python
377	Combination Sum IV	Python
378	Kth Smallest Element in a Sorted Matrix	Python
380	Insert Delete GetRandom O(1)	Python
382	Linked List Random Node	Python
383	Ransom Note	Python
384	Shuffle an Array	Python
387	First Unique Character in a String	Python
388	Longest Absolute File Path	Python
389	Find the Difference	Python
392	Is Subsequence	Java,Python
393	UTF-8 Validation	Python
394	Decode String	Python
398	Random Pick Index	Python
399	Evaluate Division	Python
401	Binary Watch	Python
402	Remove K Digits	Python
404	Sum of Left Leaves	Python
405	Convert a Number to Hexadecimal	Python
406	Queue Reconstruction by Height	Python
408	Valid Word Abbreviation	Python
409	Longest Palindrome	Python
410	Split Array Largest Sum	Python
412	Fizz Buzz	Python
413	Arithmetic Slices	Python
414	Third Maximum Number	Python
415	Add Strings	Python
416	Partition Equal Subset Sum	Python
417	Pacific Atlantic Water Flow	Python
419	Battleships in a Board	Python
421	Maximum XOR of Two Numbers in an Array	Python
422	Valid Word Square	Python
424	Longest Repeating Character Replacement	Python
425	Word Squares	Python
426	Convert Binary Search Tree to Sorted Doubly Linked List	Python
427	Construct Quad Tree	Python
429	N-ary Tree Level Order Traversal	Python
430	Flatten a Multilevel Doubly Linked List	Python
432	All O`one Data Structure	Python
433	Minimum Genetic Mutation	Python
434	Number of Segments in a String	Python
435	Non-overlapping Intervals	Python
437	Path Sum III	Java
438	Find All Anagrams in a String	Java
441	Arranging Coins	Python
442	Find All Duplicates in an Array	Python
443	String Compression	Python
445	Add Two Numbers II	Python
446	Arithmetic Slices II - Subsequence	Python
447	Number of Boomerangs	Python
448	Find All Numbers Disappeared in an Array	Java
449	Serialize and Deserialize BST	Python
451	Sort Characters By Frequency	Python
452	Minimum Number of Arrows to Burst Balloons	Python
453	Minimum Moves to Equal Array Elements	Python
454	4Sum II	Python
455	Assign Cookies	Python
456	132 Pattern	Python
458	Poor Pigs	Python
459	Repeated Substring Pattern	Python
460	LFU Cache	Python
461	Hamming Distance	Java
462	Minimum Moves to Equal Array Elements II	Python
463	Island Perimeter	Python
468	Validate IP Address	Python
473	Matchsticks to Square	Python
474	Ones and Zeroes	Python
476	Number Complement	Python
477	Total Hamming Distance	Python
478	Generate Random Point in a Circle	Python
482	License Key Formatting	Python
485	Max Consecutive Ones	Java
487	Max Consecutive Ones II	Python
489	Robot Room Cleaner	Python
491	Non-decreasing Subsequences	Python
492	Construct the Rectangle	Python
494	Target Sum	Python
495	Teemo Attacking	Python
496	Next Greater Element I	Python
498	Diagonal Traverse	Python
500	Keyboard Row	Python
501	Find Mode in Binary Search Tree	Python
503	Next Greater Element II	Java
504	Base 7	Python
506	Relative Ranks	Python
507	Perfect Number	Python
509	Fibonacci Number	Python
511	Game Play Analysis I	SQL
516	Longest Palindromic Subsequence	Python
518	Coin Change II	Python
520	Detect Capital	Python
521	Longest Uncommon Subsequence I	Python
522	Longest Uncommon Subsequence II	Python
523	Continuous Subarray Sum	Python
524	Longest Word in Dictionary through Deleting	Python
525	Contiguous Array	Python
526	Beautiful Arrangement	Python
527	Word Abbreviation	Python
528	Random Pick with Weight	Python
530	Minimum Absolute Difference in BST	Python
532	K-diff Pairs in an Array	Python
535	Encode and Decode TinyURL	Python
536	Construct Binary Tree from String	Python
537	Complex Number Multiplication	Python
538	Convert BST to Greater Tree	Java
539	Minimum Time Difference	Python
540	Single Element in a Sorted Array	Python
541	Reverse String II	Python
543	Diameter of Binary Tree	Java,Python
547	Number of Provinces	Python
551	Student Attendance Record I	Python
554	Brick Wall	Python
556	Next Greater Element III	Python
557	Reverse Words in a String III	Python
558	Logical OR of Two Binary Grids Represented as Quad-Trees	Python
559	Maximum Depth of N-ary Tree	Python
560	Subarray Sum Equals K	Java
561	Array Partition	Python
563	Binary Tree Tilt	Python
565	Array Nesting	Python
566	Reshape the Matrix	Python
567	Permutation in String	Python
572	Subtree of Another Tree	Java
575	Distribute Candies	Python
576	Out of Boundary Paths	Python
581	Shortest Unsorted Continuous Subarray	Java
584	Find Customer Referee	SQL
586	Customer Placing the Largest Number of Orders	SQL
587	Erect the Fence	Python
589	N-ary Tree Preorder Traversal	Python
590	N-ary Tree Postorder Traversal	Python
594	Longest Harmonious Subsequence	Python
595	Big Countries	SQL
596	Classes More Than 5 Students	SQL
598	Range Addition II	Python
599	Minimum Index Sum of Two Lists	Python
601	Human Traffic of Stadium	SQL
605	Can Place Flowers	Java
606	Construct String from Binary Tree	Python
607	Sales Person	SQL
609	Find Duplicate File in System	Python
611	Valid Triangle Number	Python
617	Merge Two Binary Trees	Java
620	Not Boring Movies	SQL
621	Task Scheduler	Python
623	Add One Row to Tree	Python
626	Exchange Seats	SQL
627	Swap Salary	SQL
628	Maximum Product of Three Numbers	Python
629	K Inverse Pairs Array	Python
633	Sum of Square Numbers	Python
636	Exclusive Time of Functions	Python
637	Average of Levels in Binary Tree	Python
642	Design Search Autocomplete System	Python
643	Maximum Average Subarray I	Python
645	Set Mismatch	Python
647	Palindromic Substrings	Python
653	Two Sum IV - Input is a BST	Python
654	Maximum Binary Tree	Python
657	Robot Return to Origin	Python
658	Find K Closest Elements	Python
661	Image Smoother	Python
662	Maximum Width of Binary Tree	Python
665	Non-decreasing Array	Python
667	Beautiful Arrangement II	Python
668	Kth Smallest Number in Multiplication Table	Python
669	Trim a Binary Search Tree	Python
670	Maximum Swap	Python
671	Second Minimum Node In a Binary Tree	Python
674	Longest Continuous Increasing Subsequence	Python
678	Valid Parenthesis String	Python
680	Valid Palindrome II	Python
681	Next Closest Time	Python
682	Baseball Game	Python
686	Repeated String Match	Python
687	Longest Univalue Path	Python
690	Employee Importance	Python
692	Top K Frequent Words	Python
693	Binary Number with Alternating Bits	Python
695	Max Area of Island	Python
696	Count Binary Substrings	Python
697	Degree of an Array	Python
700	Search in a Binary Search Tree	Python
701	Insert into a Binary Search Tree	Python
703	Kth Largest Element in a Stream	Python
704	Binary Search	Python
705	Design HashSet	Python
706	Design HashMap	Python
707	Design Linked List	Python
708	Insert into a Sorted Circular Linked List	Python
709	To Lower Case	Python
714	Best Time to Buy and Sell Stock with Transaction Fee	Python
717	1-bit and 2-bit Characters	Python
720	Longest Word in Dictionary	Python
721	Accounts Merge	Python
724	Find Pivot Index	Python
725	Split Linked List in Parts	Python
728	Self Dividing Numbers	Python
729	My Calendar I	Python
731	My Calendar II	Python
732	My Calendar III	Python
733	Flood Fill	Python
734	Sentence Similarity	Python
735	Asteroid Collision	Python
738	Monotone Increasing Digits	Python
739	Daily Temperatures	Python
740	Delete and Earn	Python
743	Network Delay Time	Python
744	Find Smallest Letter Greater Than Target	Python
745	Prefix and Suffix Search	Python
746	Min Cost Climbing Stairs	Python
747	Largest Number At Least Twice of Others	Python
748	Shortest Completing Word	Python
752	Open the Lock	Python
753	Cracking the Safe	Python
760	Find Anagram Mappings	Python
762	Prime Number of Set Bits in Binary Representation	Python
763	Partition Labels	Python
764	Largest Plus Sign	Python
766	Toeplitz Matrix	Python
767	Reorganize String	Python
771	Jewels and Stones	Python
777	Swap Adjacent in LR String	Python
779	K-th Symbol in Grammar	Python
783	Minimum Distance Between BST Nodes	Python
784	Letter Case Permutation	Python
785	Is Graph Bipartite?	Python
787	Cheapest Flights Within K Stops	Python
788	Rotated Digits	Python
790	Domino and Tromino Tiling	Python
791	Custom Sort String	Python
792	Number of Matching Subsequences	Python
795	Number of Subarrays with Bounded Maximum	Python
796	Rotate String	Python
797	All Paths From Source to Target	Python
799	Champagne Tower	Python
801	Minimum Swaps To Make Sequences Increasing	Python
804	Unique Morse Code Words	Python
806	Number of Lines To Write String	Python
809	Expressive Words	Python
811	Subdomain Visit Count	Python
812	Largest Triangle Area	Python
814	Binary Tree Pruning	Python
816	Ambiguous Coordinates	Python
819	Most Common Word	Python
820	Short Encoding of Words	Python
821	Shortest Distance to a Character	Python
823	Binary Trees With Factors	Python
824	Goat Latin	Python
825	Friends Of Appropriate Ages	Python
827	Making A Large Island	Python
830	Positions of Large Groups	Python
832	Flipping an Image	Java
833	Find And Replace in String	Python
834	Sum of Distances in Tree	Python
836	Rectangle Overlap	Python
837	New 21 Game	Python
840	Magic Squares In Grid	Python
841	Keys and Rooms	Python
843	Guess the Word	Python
844	Backspace String Compare	Python
847	Shortest Path Visiting All Nodes	Python
848	Shifting Letters	Python
849	Maximize Distance to Closest Person	Python
852	Peak Index in a Mountain Array	Python
856	Score of Parentheses	Python
857	Minimum Cost to Hire K Workers	Python
858	Mirror Reflection	Python
859	Buddy Strings	Python
860	Lemonade Change	Python
863	All Nodes Distance K in Binary Tree	Python
865	Smallest Subtree with all the Deepest Nodes	Python
867	Transpose Matrix	Python
868	Binary Gap	Python
871	Minimum Number of Refueling Stops	Python
872	Leaf-Similar Trees	Java
874	Walking Robot Simulation	Java
875	Koko Eating Bananas	Python
876	Middle of the Linked List	Python
877	Stone Game	Python
880	Decoded String at Index	Python
881	Boats to Save People	Python
883	Projection Area of 3D Shapes	Java
884	Uncommon Words from Two Sentences	Python
885	Spiral Matrix III	Python
886	Possible Bipartition	Python
888	Fair Candy Swap	Python
890	Find and Replace Pattern	Python
892	Surface Area of 3D Shapes	Python
893	Groups of Special-Equivalent Strings	Python
894	All Possible Full Binary Trees	Python
895	Maximum Frequency Stack	Python
896	Monotonic Array	Python
897	Increasing Order Search Tree	Python
899	Orderly Queue	Python
900	RLE Iterator	Python
901	Online Stock Span	Python
904	Fruit Into Baskets	Python
905	Sort Array By Parity	Python
907	Sum of Subarray Minimums	Python
908	Smallest Range I	Python
914	X of a Kind in a Deck of Cards	Python
915	Partition Array into Disjoint Intervals	Python
916	Word Subsets	Python
917	Reverse Only Letters	Python
918	Maximum Sum Circular Subarray	Python
921	Minimum Add to Make Parentheses Valid	Python
922	Sort Array By Parity II	Python
925	Long Pressed Name	Python
929	Unique Email Addresses	Python
931	Minimum Falling Path Sum	Python
932	Beautiful Array	Python
933	Number of Recent Calls	Python
935	Knight Dialer	Python
938	Range Sum of BST	Python
939	Minimum Area Rectangle	Python
941	Valid Mountain Array	Python
942	DI String Match	Python
944	Delete Columns to Make Sorted	Python
946	Validate Stack Sequences	Python
947	Most Stones Removed with Same Row or Column	Python
948	Bag of Tokens	Python
949	Largest Time for Given Digits	Python
951	Flip Equivalent Binary Trees	Python
953	Verifying an Alien Dictionary	Python
958	Check Completeness of a Binary Tree	Python
961	N-Repeated Element in Size 2N Array	Python
962	Maximum Width Ramp	Python
963	Minimum Area Rectangle II	Python
965	Univalued Binary Tree	Python
966	Vowel Spellchecker	Python
967	Numbers With Same Consecutive Differences	Python
968	Binary Tree Cameras	Python
970	Powerful Integers	Python
973	K Closest Points to Origin	Python
975	Odd Even Jump	Python
976	Largest Perimeter Triangle	Python
977	Squares of a Sorted Array	Python
980	Unique Paths III	Python
981	Time Based Key-Value Store	Python
985	Sum of Even Numbers After Queries	Python
986	Interval List Intersections	Python
987	Vertical Order Traversal of a Binary Tree	Python
989	Add to Array-Form of Integer	Python
991	Broken Calculator	Python
993	Cousins in Binary Tree	Python
997	Find the Town Judge	Python
999	Available Captures for Rook	Python
1002	Find Common Characters	Python
1004	Max Consecutive Ones III	Python
1005	Maximize Sum Of Array After K Negations	Python
1007	Minimum Domino Rotations For Equal Row	Python
1008	Construct Binary Search Tree from Preorder Traversal	Python
1009	Complement of Base 10 Integer	Python
1010	Pairs of Songs With Total Durations Divisible by 60	Python
1013	Partition Array Into Three Parts With Equal Sum	Python
1015	Smallest Integer Divisible by K	Python
1018	Binary Prefix Divisible By 5	Python
1019	Next Greater Node In Linked List	Python
1021	Remove Outermost Parentheses	Python
1022	Sum of Root To Leaf Binary Numbers	Python
1025	Divisor Game	Python
1026	Maximum Difference Between Node and Ancestor	Python
1027	Longest Arithmetic Subsequence	Python
1029	Two City Scheduling	Python
1030	Matrix Cells in Distance Order	Python
1032	Stream of Characters	Python
1035	Uncrossed Lines	Python
1037	Valid Boomerang	Python
1044	Longest Duplicate Substring	Python
1046	Last Stone Weight	Python
1047	Remove All Adjacent Duplicates In String	Python
1048	Longest String Chain	Python
1049	Last Stone Weight II	Python
1050	Actors and Directors Who Cooperated At Least Three Times	SQL
1051	Height Checker	Python
1055	Shortest Way to Form String	Python
1057	Campus Bikes	Python
1064	Fixed Point	Python
1066	Campus Bikes II	Python
1071	Greatest Common Divisor of Strings	Python
1074	Number of Submatrices That Sum to Target	Python
1078	Occurrences After Bigram	Python
1081	Smallest Subsequence of Distinct Characters	Python
1084	Sales Analysis III	SQL
1089	Duplicate Zeros	Python
1091	Shortest Path in Binary Matrix	Python
1094	Car Pooling	Python
1103	Distribute Candies to People	Python
1108	Defanging an IP Address	Python
1114	Print in Order	Python
1122	Relative Sort Array	Python
1123	Lowest Common Ancestor of Deepest Leaves	Python
1128	Number of Equivalent Domino Pairs	Python
1137	N-th Tribonacci Number	Python
1141	User Activity for the Past 30 Days I	SQL
1143	Longest Common Subsequence	Python
1148	Article Views I	SQL
1154	Day of the Year	Python
1155	Number of Dice Rolls With Target Sum	Python
1160	Find Words That Can Be Formed by Characters	Python
1178	Number of Valid Words for Each Puzzle	Python
1179	Reformat Department Table
1184	Distance Between Bus Stops	Python
1185	Day of the Week	Python
1189	Maximum Number of Balloons	Python
1192	Critical Connections in a Network	Python
1200	Minimum Absolute Difference	Python
1202	Smallest String With Swaps	Python
1207	Unique Number of Occurrences	Python
1209	Remove All Adjacent Duplicates in String II	Python
1217	Minimum Cost to Move Chips to The Same Position	Python
1220	Count Vowels Permutation	Python
1221	Split a String in Balanced Strings	Python
1232	Check If It Is a Straight Line	Python
1235	Maximum Profit in Job Scheduling	Python
1249	Minimum Remove to Make Valid Parentheses	Python
1252	Cells with Odd Values in a Matrix	Python
1260	Shift 2D Grid	Python
1266	Minimum Time Visiting All Points	Python
1268	Search Suggestions System	Python
1277	Count Square Submatrices with All Ones	Python
1283	Find the Smallest Divisor Given a Threshold	Python
1286	Iterator for Combination	Python
1288	Remove Covered Intervals	Python
1290	Convert Binary Number in a Linked List to Integer	Python
1302	Deepest Leaves Sum	Python
1306	Jump Game III	Python
1323	Maximum 69 Number	Python
1332	Remove Palindromic Subsequences	Python
1337	The K Weakest Rows in a Matrix	Python
1338	Reduce Array Size to The Half	Python
1339	Maximum Product of Splitted Binary Tree	Python
1342	Number of Steps to Reduce a Number to Zero	Python
1344	Angle Between Hands of a Clock	Python
1345	Jump Game IV	Python
1359	Count All Valid Pickup and Delivery Options	Python
1379	Find a Corresponding Node of a Binary Tree in a Clone of That Tree	Python
1383	Maximum Performance of a Team	Python
1396	Design Underground System	Python
1413	Minimum Value to Get Positive Step by Step Sum	Python
1426	Counting Elements	Python
1427	Perform String Shifts	Python
1428	Leftmost Column with at Least a One	Python
1429	First Unique Number	Python
1430	Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree	Python
1446	Consecutive Characters	Python
1448	Count Good Nodes in Binary Tree	Python
1457	Pseudo-Palindromic Paths in a Binary Tree	Python
1461	Check If a String Contains All Binary Codes of Size K	Python
1465	Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts	Python
1473	Paint House III	Python
1480	Running Sum of 1d Array	Python
1492	The kth Factor of n	Python
1510	Stone Game IV	Python
1539	Kth Missing Positive Number	Python
1544	Make The String Great	Python
1551	Minimum Operations to Make Array Equal	Python
1578	Minimum Time to Make Rope Colorful	Python
1629	Slowest Key	Python
1631	Path With Minimum Effort	Python
1640	Check Array Formation Through Concatenation	Python
1641	Count Sorted Vowel Strings	Python
1642	Furthest Building You Can Reach	Python
1657	Determine if Two Strings Are Close	Python
1662	Check If Two String Arrays are Equivalent	Python
1663	Smallest String With A Given Numeric Value	Python
1675	Minimize Deviation in Array	Python
1679	Max Number of K-Sum Pairs	Python
1689	Partitioning Into Minimum Number Of Deci-Binary Numbers	Python
1690	Stone Game VII	Python
1695	Maximum Erasure Value	Python
1696	Jump Game VI	Python
1704	Determine if String Halves Are Alike	Python
1706	Where Will the Ball Fall	Python
1710	Maximum Units on a Truck	Python
1721	Swapping Nodes in a Linked List	Python
1834	Single-Threaded CPU	Python
1926	Nearest Exit from Entrance in Maze	Python
1962	Remove Stones to Minimize the Total	Python
1971	Find if Path Exists in Graph	Python
1996	The Number of Weak Characters in the Game	Python
2007	Find Original Array From Doubled Array	Python
2154	Keep Multiplying Found Values by Two	Python
2160	Minimum Sum of Four Digit Number After Splitting Digits	Python
2164	Sort Even and Odd Indices Independently	Python
2169	Count Operations to Obtain Zero	Python
2176	Count Equal and Divisible Pairs in an Array	Python
2180	Count Integers With Even Digit Sum	Python
2185	Counting Words With a Given Prefix	Python
2225	Find Players With Zero or One Losses	Python
2256	Minimum Average Difference	Python
2279	Maximum Bags With Full Capacity of Rocks	Python
2389	Longest Subsequence With Limited Sum	Python

Features

• Contains a lot of interview questions and still constantly adding!
• Many languages are used for problems -- you can choose what you want!

Quick Start

Clone it. Have a look at the solutions or some particular question and get inpired!

Contribution Guide

You can choose any problem in LeetCode and bring your solution here. However, notice the folder structure of current repo

--questions          # root folder for questions
  --3sum             # named after the question title slug
    --Solution.java  # actual code for the solution. the problem description and maybe even explanation
                     #   for the solution are in the form of comments

1. Fork the repository.
2. Solve the problem in LeetCode.
3. Create the solution file in the correct directory and add the link to README table.
4. Create pull request.
5. After review and discussions, the patch will be merged!

Question and Help

You are welcome to use Issue Trackers in the repository to bring up any questions!

License

MIT license. You are free to contribute or hack!