/leetcode-1

Solutions to all LeetCode problems: Algorithms/Ruby, Database/MySQL, Shell/Bash

Primary LanguageRubyMIT LicenseMIT

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