LeetCode

#	Title	Solution	Difficulty
526	Beautiful Arrangement		Medium
525	Contiguous Array		Medium
524
523
522
521
520	Detect Capital	Ruby	Easy
519
518
517	Super Washing Machines		Hard
516	Longest Palindromic Subsequence		Medium
515	Find Largest Value in Each Tree Row		Medium
514
513	Find Bottom Left Tree Value		Medium
512
511
510
509
508	Most Frequent Subtree Sum		Medium
507
506	Relative Ranks	Ruby	Easy
505	The Maze II	🔒	Medium
504	Base 7	Ruby	Easy
503	Next Greater Element II		Medium
502	IPO		Hard
501	Find Mode in Binary Search Tree	Ruby	Easy
500	Keyboard Row	Ruby	Easy
499	The Maze III		Hard
498	Diagonal Traverse		Medium
497
496	Next Greater Element I		Easy
495	Teemo Attacking		Medium
494	Target Sum		Medium
493	Reverse Pairs		Hard
492	Construct the Rectangle		Easy
491	Increasing Subsequences		Medium
490	The Maze	🔒	Medium
489
488	Zuma Game		Hard
487	Max Consecutive Ones II	🔒	Medium
486	Predict the Winner		Medium
485	Max Consecutive Ones		Easy
484	Find Permutation	🔒	Medium
483	Smallest Good Base		Hard
482	License Key Formatting		Medium
481	Magical String		Medium
480	Sliding Window Median		Hard
479
478
477	Total Hamming Distance		Medium
476	Number Complement		Easy
475	Heaters		Easy
474	Ones and Zeroes		Medium
473	Matchsticks to Square		Medium
472	Concatenated Words		Hard
471	Encode String with Shortest Length	🔒	Hard
470
469	Convex Polygon	🔒	Medium
468	Validate IP Address	Ruby	Medium
467	Unique Substrings in Wraparound String		Medium
466	Count The Repetitions		Hard
465	Optimal Account Balancing	🔒	Hard
464	Can I Win		Medium
463	Island Perimeter		Easy
462	Minimum Moves to Equal Array Elements II		Medium
461	Hamming Distance		Easy
460	LFU Cache		Hard
459	Repeated Substring Pattern		Easy
458
457
456	132 Pattern		Medium
455	Assign Cookies	Ruby	Easy
454	4Sum II		Medium
453	Minimum Moves to Equal Array Elements	Ruby	Easy
452	Minimum Number of Arrows to Burst Balloons		Medium
451	Sort Characters By Frequency	Ruby	Medium
450	Delete Node in a BST		Medium
449	Serialize and Deserialize BST	Ruby	Medium
448	Find All Numbers Disappeared in an Array	Ruby	Easy
447	Number of Boomerangs		Easy
446	Arithmetic Slices II - Subsequence		Hard
445	Add Two Numbers II		Medium
444	Sequence Reconstruction	🔒	Medium
443
442	Find All Duplicates in an Array		Medium
441	Arranging Coins		Easy
440	K-th Smallest in Lexicographical Order		Hard
439	Ternary Expression Parser	🔒	Medium
438	Find All Anagrams in a String		Easy
437	Path Sum III		Easy
436	Find Right Interval		Medium
435	Non-overlapping Intervals		Medium
434	Number of Segments in a String		Easy
433
432	All O(1) Data Structure		Hard
431
430
429
428
427
426
425	Word Squares	🔒	Hard
424	Longest Repeating Character Replacement		Medium
423	Reconstruct Original Digits from English		Medium
422	Valid Word Square	🔒	Easy
421	Maximum XOR of Two Numbers in an Array		Medium
420	Strong Password Checker		Hard
419	Battleships in a Board		Medium
418	Sentence Screen Fitting	🔒	Medium
417	Pacific Atlantic Water Flow		Medium
416	Partition Equal Subset Sum		Medium
415	Add Strings		Easy
414	Third Maximum Number		Easy
413	Arithmetic Slices		Medium
412	Fizz Buzz	Ruby	Easy
411	Minimum Unique Word Abbreviation	🔒	Hard
410	Split Array Largest Sum		Hard
409	Longest Palindrome	Ruby	Easy
408	Valid Word Abbreviation	🔒	Easy
407	Trapping Rain Water II		Hard
406	Queue Reconstruction by Height		Medium
405	Convert a Number to Hexadecimal	Ruby	Easy
404	Sum of Left Leaves	Ruby	Easy
403	Frog Jump		Hard
402	Remove K Digits		Medium
401	Binary Watch		Easy
400	Nth Digit		Easy
399	Evaluate Division		Medium
398	Random Pick Index	🔜	Medium
397	Integer Replacement		Medium
396	Rotate Function	Ruby	Easy
395	Longest Substring with At Least K Repeating Characters		Medium
394	Decode String	Ruby	Medium
393	UTF-8 Validation	Ruby	Medium
392	Is Subsequence		Medium
391	Perfect Rectangle		Hard
390	Elimination Game		Medium
389	Find the Difference	Ruby	Easy
388	Longest Absolute File Path		Medium
387	First Unique Character in a String	Ruby	Easy
386	Lexicographical Numbers	🔜	Medium
385	Mini Parser	Ruby	Medium
384	Shuffle an Array	🔜	Medium
383	Ransom Note	Ruby	Easy
382	Linked List Random Node	🔜	Medium
381	Insert Delete GetRandom O(1) - Duplicates allowed	🔜	Hard
380	Insert Delete GetRandom O(1)	🔜	Hard
379	Design Phone Directory	🔒	Medium
378	Kth Smallest Element in a Sorted Matrix		Medium
377	Combination Sum IV		Medium
376	Wiggle Subsequence		Medium
375	Guess Number Higher or Lower II		Medium
374	Guess Number Higher or Lower	🔜	Easy
373	Find K Pairs with Smallest Sums		Medium
372	Super Pow		Medium
371	Sum of Two Integers	Ruby	Easy
370	Range Addition	🔒	Medium
369	Plus One Linked List	🔒	Medium
368	Largest Divisible Subset		Medium
367	Valid Perfect Square	Ruby	Easy
366	Find Leaves of Binary Tree	🔒	Medium
365	Water and Jug Problem		Medium
364	Nested List Weight Sum II	🔒	Medium
363	Max Sum of Rectangle No Larger Than K		Hard
362	Design Hit Counter	🔒	Medium
361	Bomb Enemy	🔒	Medium
360	Sort Transformed Array	🔒	Medium
359	Logger Rate Limiter	🔒	Easy
358	Rearrange String k Distance Apart	🔒	Hard
357	Count Numbers with Unique Digits		Medium
356	Line Reflection	🔒	Medium
355	Design Twitter	🔜	Medium
354	Russian Doll Envelopes		Hard
353	Design Snake Game	🔒	Medium
352	Data Stream as Disjoint Intervals	🔜	Hard
351	Android Unlock Patterns	🔒	Medium
350	Intersection of Two Arrays II	Ruby	Easy
349	Intersection of Two Arrays	Ruby	Easy
348	Design Tic-Tac-Toe	🔒	Medium
347	Top K Frequent Elements	Ruby	Medium
346	Moving Average from Data Stream	🔒	Easy
345	Reverse Vowels of a String	Ruby	Easy
344	Reverse String	Ruby	Easy
343	Integer Break	Ruby	Medium
342	Power of Four	Ruby	Easy
341	Flatten Nested List Iterator	🔒	Medium
340	Longest Substring with At Most K Distinct Characters	🔒	Hard
339	Nested List Weight Sum	🔒	Easy
338	Counting Bits	Ruby	Medium
337	House Robber III	Ruby	Medium
336	Palindrome Pairs	Ruby	Hard
335	Self Crossing	Ruby	Medium
334	Increasing Triplet Subsequence	Ruby	Medium
333	Largest BST Subtree	🔒	Medium
332	Reconstruct Itinerary	Ruby	Medium
331	Verify Preorder Serialization of a Binary Tree	Ruby	Medium
330	Patching Array	Ruby	Medium
329	Longest Increasing Path in a Matrix	Ruby	Medium
328	Odd Even Linked List	Ruby	Easy
327	Count of Range Sum	Ruby	Hard
326	Power of Three	Ruby	Easy
325	Maximum Size Subarray Sum Equals k	🔒	Easy
324	Wiggle Sort II	Ruby	Medium
323	Number of Connected Components in an Undirected Graph	🔒	Easy
322	Coin Change	Ruby	Medium
321	Create Maximum Number	Ruby	Hard
320	Generalized Abbreviation	🔒	Medium
319	Bulb Switcher	Ruby	Medium
318	Maximum Product of Word Lengths	Ruby	Medium
317	Shortest Distance from All Buildings	🔒	Hard
316	Remove Duplicate Letters	Ruby	Medium
315	Count of Smaller Numbers After Self	Ruby	Hard
314	Binary Tree Vertical Order Traversal	🔒	Medium
313	Super Ugly Number	Ruby	Medium
312	Burst Balloons	Ruby	Medium
311	Sparse Matrix Multiplication	🔒	Medium
310	Minimum Height Trees	Ruby	Medium
309	Best Time to Buy and Sell Stock with Cooldown	Ruby	Medium
308	Range Sum Query 2D - Mutable	🔒	Hard
307	Range Sum Query - Mutable	Ruby	Medium
306	Additive Number	Ruby	Medium
305	Number of Islands II	🔒	Hard
304	Range Sum Query 2D - Immutable	Ruby	Medium
303	Range Sum Query - Immutable	Ruby	Easy
302	Smallest Rectangle Enclosing Black Pixels	🔒	Medium
301	Remove Invalid Parentheses	Ruby	Medium
300	Longest Increasing Subsequence	Ruby	Medium
299	Bulls and Cows	Ruby	Easy
298	Binary Tree Longest Consecutive Sequence	🔒	Medium
297	Serialize and Deserialize Binary Tree	Ruby	Medium
296	Best Meeting Point	🔒	Medium
295	Find Median from Data Stream	Ruby	Hard
294	Flip Game II	🔒	Medium
293	Flip Game	🔒	Easy
292	Nim Game	Ruby	Easy
291	Word Pattern II	🔒	Hard
290	Word Pattern	Ruby	Easy
289	Game of Life	Ruby	Medium
288	Unique Word Abbreviation	🔒	Easy
287	Find the Duplicate Number	Ruby	Hard
286	Walls and Gates	🔒	Medium
285	Inorder Successor in BST	🔒	Medium
284	Peeking Iterator	🔜	Medium
283	Move Zeroes	Ruby	Easy
282	Expression Add Operators	Ruby	Hard
281	Zigzag Iterator	🔒	Medium
280	Wiggle Sort	🔒	Medium
279	Perfect Squares	Ruby	Medium
278	First Bad Version	Ruby	Easy
277	Find the Celebrity	🔒	Medium
276	Paint Fence	🔒	Easy
275	H-Index II	Ruby	Medium
274	H-Index	Ruby	Medium
273	Integer to English Words	Ruby	Medium
272	Closest Binary Search Tree Value II	🔒	Hard
271	Encode and Decode Strings	🔒	Medium
270	Closest Binary Search Tree Value	🔒	Easy
269	Alien Dictionary	🔒	Hard
268	Missing Number	Ruby	Medium
267	Palindrome Permutation II	🔒	Medium
266	Palindrome Permutation	🔒	Easy
265	Paint House II	🔒	Hard
264	Ugly Number II	Ruby	Medium
263	Ugly Number	Ruby	Easy
262	Trips and Users	MySQL	Hard
261	Graph Valid Tree	🔒	Medium
260	Single Number III	Ruby	Medium
259	3Sum Smaller	🔒	Medium
258	Add Digits	Ruby	Easy
257	Binary Tree Paths	Ruby	Easy
256	Paint House	🔒	Medium
255	Verify Preorder Sequence in Binary Search Tree	🔒	Medium
254	Factor Combinations	🔒	Medium
253	Meeting Rooms II	🔒	Medium
252	Meeting Rooms	🔒	Easy
251	Flatten 2D Vector	🔒	Medium
250	Count Univalue Subtrees	🔒	Medium
249	Group Shifted Strings	🔒	Easy
248	Strobogrammatic Number III	🔒	Hard
247	Strobogrammatic Number II	🔒	Medium
246	Strobogrammatic Number	🔒	Easy
245	Shortest Word Distance III	🔒	Medium
244	Shortest Word Distance II	🔒	Medium
243	Shortest Word Distance	🔒	Easy
242	Valid Anagram	Ruby	Easy
241	Different Ways to Add Parentheses	Ruby	Medium
240	Search a 2D Matrix II	Ruby	Medium
239	Sliding Window Maximum	Ruby	Hard
238	Product of Array Except Self	Ruby	Medium
237	Delete Node in a Linked List	Ruby	Easy
236	Lowest Common Ancestor of a Binary Tree	Ruby	Medium
235	Lowest Common Ancestor of a Binary Search Tree	Ruby	Easy
234	Palindrome Linked List	Ruby	Easy
233	Number of Digit One	Ruby	Medium
232	Implement Queue using Stacks	Ruby	Easy
231	Power of Two	Ruby	Easy
230	Kth Smallest Element in a BST	Ruby	Medium
229	Majority Element II	Ruby	Medium
228	Summary Ranges	Ruby	Easy
227	Basic Calculator II	Ruby	Medium
226	Invert Binary Tree	Ruby	Easy
225	Implement Stack using Queues	Ruby	Easy
224	Basic Calculator	Ruby	Medium
223	Rectangle Area	Ruby	Easy
222	Count Complete Tree Nodes	Ruby	Medium
221	Maximal Square	Ruby	Medium
220	Contains Duplicate III	Ruby	Medium
219	Contains Duplicate II	Ruby	Easy
218	The Skyline Problem	Ruby	Hard
217	Contains Duplicate	Ruby	Easy
216	Combination Sum III	Ruby	Medium
215	Kth Largest Element in an Array	Ruby	Medium
214	Shortest Palindrome	Ruby	Hard
213	House Robber II	Ruby	Medium
212	Word Search II	Ruby	Hard
211	Add and Search Word - Data structure design	Ruby	Medium
210	Course Schedule II	Ruby	Medium
209	Minimum Size Subarray Sum	Ruby	Medium
208	Implement Trie (Prefix Tree)	Ruby	Medium
207	Course Schedule	Ruby	Medium
206	Reverse Linked List	Ruby	Easy
205	Isomorphic Strings	Ruby	Easy
204	Count Primes	Ruby	Easy
203	Remove Linked List Elements	Ruby	Easy
202	Happy Number	Ruby	Easy
201	Bitwise AND of Numbers Range	Ruby	Medium
200	Number of Islands	Ruby	Medium
199	Binary Tree Right Side View	Ruby	Medium
198	House Robber	Ruby	Easy
197	Rising Temperature	MySQL	Easy
196	Delete Duplicate Emails	MySQL	Easy
195	Tenth Line	Bash	Easy
194	Transpose File	Bash	Medium
193	Valid Phone Numbers	Bash	Easy
192	Word Frequency	Bash	Medium
191	Number of 1 Bits	Ruby	Easy
190	Reverse Bits	Ruby	Easy
189	Rotate Array	Ruby	Easy
188	Best Time to Buy and Sell Stock IV	Ruby	Hard
187	Repeated DNA Sequences	Ruby	Medium
186	Reverse Words in a String II	🔒	Medium
185	Department Top Three Salaries	MySQL	Hard
184	Department Highest Salary	MySQL	Medium
183	Customers Who Never Order	MySQL	Easy
182	Duplicate Emails	MySQL	Easy
181	Employees Earning More Than Their Managers	MySQL	Easy
180	Consecutive Numbers	MySQL	Medium
179	Largest Number	Ruby	Medium
178	Rank Scores	MySQL	Medium
177	Nth Highest Salary	MySQL	Medium
176	Second Highest Salary	MySQL	Easy
175	Combine Two Tables	MySQL	Easy
174	Dungeon Game	Ruby	Hard
173	Binary Search Tree Iterator	Ruby	Medium
172	Factorial Trailing Zeroes	Ruby	Easy
171	Excel Sheet Column Number	Ruby	Easy
170	Two Sum III - Data structure design	🔒	Easy
169	Majority Element	Ruby	Easy
168	Excel Sheet Column Title	Ruby	Easy
167	Two Sum II - Input array is sorted	🔒	Medium
166	Fraction to Recurring Decimal	Ruby	Medium
165	Compare Version Numbers	Ruby	Easy
164	Maximum Gap	Ruby	Hard
163	Missing Ranges	🔒	Medium
162	Find Peak Element	Ruby	Medium
161	One Edit Distance	🔒	Medium
160	Intersection of Two Linked Lists	🔜	Easy
159	Longest Substring with At Most Two Distinct Characters	🔒	Hard
158	Read N Characters Given Read4 II - Call multiple times	🔒	Hard
157	Read N Characters Given Read4	🔒	Easy
156	Binary Tree Upside Down	🔒	Medium
155	Min Stack	Ruby	Easy
154	Find Minimum in Rotated Sorted Array II	Ruby	Hard
153	Find Minimum in Rotated Sorted Array	Ruby	Medium
152	Maximum Product Subarray	Ruby	Medium
151	Reverse Words in a String	🔜	Medium
150	Evaluate Reverse Polish Notation	Ruby	Medium
149	Max Points on a Line	Ruby	Hard
148	Sort List	Ruby	Medium
147	Insertion Sort List	Ruby	Medium
146	LRU Cache	Ruby	Hard
145	Binary Tree Postorder Traversal	Ruby	Hard
144	Binary Tree Preorder Traversal	Ruby	Medium
143	Reorder List	Ruby	Medium
142	Linked List Cycle II	🔜	Medium
141	Linked List Cycle	🔜	Medium
140	Word Break II	Ruby	Hard
139	Word Break	Ruby	Medium
138	Copy List with Random Pointer	🔜	Hard
137	Single Number II	Ruby	Medium
136	Single Number	Ruby	Medium
135	Candy	Ruby	Hard
134	Gas Station	Ruby	Medium
133	Clone Graph	🔜	Medium
132	Palindrome Partitioning II	Ruby	Hard
131	Palindrome Partitioning	Ruby	Medium
130	Surrounded Regions	Ruby	Medium
129	Sum Root to Leaf Numbers	Ruby	Medium
128	Longest Consecutive Sequence	Ruby	Hard
127	Word Ladder	Ruby	Medium
126	Word Ladder II	🔜	Hard
125	Valid Palindrome	Ruby	Easy
124	Binary Tree Maximum Path Sum	Ruby	Hard
123	Best Time to Buy and Sell Stock III	Ruby	Hard
122	Best Time to Buy and Sell Stock II	Ruby	Medium
121	Best Time to Buy and Sell Stock	Ruby	Medium
120	Triangle	Ruby	Medium
119	Pascal's Triangle II	Ruby	Easy
118	Pascal's Triangle	Ruby	Easy
117	Populating Next Right Pointers in Each Node II	🔜	Hard
116	Populating Next Right Pointers in Each Node	🔜	Medium
115	Distinct Subsequences	Ruby	Hard
114	Flatten Binary Tree to Linked List	Ruby	Medium
113	Path Sum II	Ruby	Medium
112	Path Sum	Ruby	Easy
111	Minimum Depth of Binary Tree	Ruby	Easy
110	Balanced Binary Tree	Ruby	Easy
109	Convert Sorted List to Binary Search Tree	Ruby	Medium
108	Convert Sorted Array to Binary Search Tree	Ruby	Medium
107	Binary Tree Level Order Traversal II	Ruby	Easy
106	Construct Binary Tree from Inorder and Postorder Traversal	Ruby	Medium
105	Construct Binary Tree from Preorder and Inorder Traversal	Ruby	Medium
104	Maximum Depth of Binary Tree	Ruby	Easy
103	Binary Tree Zigzag Level Order Traversal	Ruby	Medium
102	Binary Tree Level Order Traversal	Ruby	Easy
101	Symmetric Tree	Ruby	Easy
100	Same Tree	Ruby	Easy
99	Recover Binary Search Tree	Ruby	Hard
98	Validate Binary Search Tree	Ruby	Medium
97	Interleaving String	Ruby	Hard
96	Unique Binary Search Trees	Ruby	Medium
95	Unique Binary Search Trees II	Ruby	Medium
94	Binary Tree Inorder Traversal	Ruby	Medium
93	Restore IP Addresses	Ruby	Medium
92	Reverse Linked List II	Ruby	Medium
91	Decode Ways	Ruby	Medium
90	Subsets II	Ruby	Medium
89	Gray Code	Ruby	Medium
88	Merge Sorted Array	Ruby	Easy
87	Scramble String	Ruby	Hard
86	Partition List	Ruby	Medium
85	Maximal Rectangle	Ruby	Hard
84	Largest Rectangle in Histogram	Ruby	Hard
83	Remove Duplicates from Sorted List	Ruby	Easy
82	Remove Duplicates from Sorted List II	Ruby	Medium
81	Search in Rotated Sorted Array II	Ruby	Medium
80	Remove Duplicates from Sorted Array II	Ruby	Medium
79	Word Search	Ruby	Medium
78	Subsets	Ruby	Medium
77	Combinations	Ruby	Medium
76	Minimum Window Substring	Ruby	Hard
75	Sort Colors	Ruby	Medium
74	Search a 2D Matrix	Ruby	Medium
73	Set Matrix Zeroes	Ruby	Medium
72	Edit Distance	Ruby	Hard
71	Simplify Path	Ruby	Medium
70	Climbing Stairs	Ruby	Easy
69	Sqrt()	Ruby	Medium
68	Text Justification	Ruby	Hard
67	Add Binary	Ruby	Easy
66	Plus One	Ruby	Easy
65	Valid Number	Ruby	Hard
64	Minimum Path Sum	Ruby	Medium
63	Unique Paths II	Ruby	Medium
62	Unique Paths	Ruby	Medium
61	Rotate List	Ruby	Medium
60	Permutation Sequence	Ruby	Medium
59	Spiral Matrix II	Ruby	Medium
58	Length of Last Word	Ruby	Easy
57	Insert Interval	Ruby	Hard
56	Merge Intervals	Ruby	Hard
55	Jump Game	Ruby	Medium
54	Spiral Matrix	Ruby	Medium
53	Maximum Subarray	Ruby	Medium
52	N-Queens II	Ruby	Hard
51	N-Queens	Ruby	Hard
50	Pow(x, n)	Ruby	Medium
49	Group Anagrams	Ruby	Medium
48	Rotate Image	Ruby	Medium
47	Permutations II	Ruby	Medium
46	Permutations	Ruby	Medium
45	Jump Game II	Ruby	Hard
44	Wildcard Matching	Ruby	Hard
43	Multiply Strings	Ruby	Medium
42	Trapping Rain Water	Ruby	Hard
41	First Missing Positive	Ruby	Hard
40	Combination Sum II	Ruby	Medium
39	Combination Sum	Ruby	Medium
38	Count and Say	Ruby	Easy
37	Sudoku Solver	Ruby	Hard
36	Valid Sudoku	Ruby	Easy
35	Search Insert Position	Ruby	Medium
34	Search for a Range	Ruby	Medium
33	Search in Rotated Sorted Array	Ruby	Hard
32	Longest Valid Parentheses	Ruby	Hard
31	Next Permutation	Ruby	Medium
30	Substring with Concatenation of All Words	Ruby	Hard
29	Divide Two Integers	Ruby	Medium
28	Implement strStr()	Ruby	Easy
27	Remove Element	Ruby	Easy
26	Remove Duplicates from Sorted Array	Ruby	Easy
25	Reverse Nodes in k-Group	Ruby	Hard
24	Swap Nodes in Pairs	Ruby	Medium
23	Merge k Sorted Lists	Ruby	Hard
22	Generate Parentheses	Ruby	Medium
21	Merge Two Sorted Lists	Ruby	Easy
20	Valid Parentheses	Ruby	Easy
19	Remove Nth Node From End of List	Ruby	Easy
18	4Sum	Ruby	Medium
17	Letter Combinations of a Phone Number	Ruby	Medium
16	3Sum Closest	Ruby	Medium
15	3Sum	Ruby	Medium
14	Longest Common Prefix	Ruby	Easy
13	Roman to Integer	Ruby	Easy
12	Integer to Roman	Ruby	Medium
11	Container With Most Water	Ruby	Medium
10	Regular Expression Matching	Ruby	Hard
9	Palindrome Number	Ruby	Easy
8	String to Integer (atoi)	Ruby	Easy
7	Reverse Integer	Ruby	Easy
6	ZigZag Conversion	Ruby	Easy
5	Longest Palindromic Substring	Ruby	Medium
4	Median of Two Sorted Arrays	Ruby	Hard
3	Longest Substring Without Repeating Characters	Ruby	Medium
2	Add Two Numbers	Ruby	Medium
1	Two Sum	Ruby	Medium