Overview

My solutions to LeetCode problems.

Problems

1. Two Sum

Tags: Array Hash Table
Code: C# Go Python

2. Add Two Numbers

Tags: Linked List Math Recursion
Code: C# Go Python

3. Longest Substring Without Repeating Characters

Tags: Hash Table String Sliding Window
Code: C# Go Python

4. Median of Two Sorted Arrays

Tags: Array Binary Search Divide and Conquer
Code: C# Python

5. Longest Palindromic Substring

Tags: String Dynamic Programming
Code: C# Python

6. Zigzag Conversion

Tags: String
Code: C# Go Python

7. Reverse Integer

Tags: Math
Code: C# Go Python

9. Palindrome Number

Tags: Math
Code: C# Go Python

11. Container With Most Water

Tags: Array Two Pointers Greedy
Code: C# Go

12. Integer to Roman

Tags: Hash Table Math String
Code: C# Go Python Rust

13. Roman to Integer

Tags: Hash Table Math String
Code: C# Go Python Rust

14. Longest Common Prefix

Tags: String Trie
Code: C#

15. 3Sum

Tags: Array Two Pointers Sorting
Code: C# Go

16. 3Sum Closest

Tags: Array Two Pointers Sorting
Code: C#

17. Letter Combinations of a Phone Number

Tags: Hash Table String Backtracking
Code: C# Go Python TypeScript JavaScript

19. Remove Nth Node From End of List

Tags: Linked List Two Pointers
Code: C#

20. Valid Parentheses

Tags: String Stack
Code: C# Go

21. Merge Two Sorted Lists

Tags: Linked List Recursion
Code: C# Go Python

22. Generate Parentheses

Tags: String Dynamic Programming Backtracking
Code: C# Go Python

23. Merge k Sorted Lists

Tags: Linked List Divide and Conquer Heap (Priority Queue) Merge Sort
Code: C# Go Python

24. Swap Nodes in Pairs

Tags: Linked List Recursion
Code: C# Python

25. Reverse Nodes in k-Group

Tags: Linked List Recursion
Code: C# Python

26. Remove Duplicates from Sorted Array

Tags: Array Two Pointers
Code: C# Go Python Rust

27. Remove Element

Tags: Array Two Pointers
Code: C# Go Python Rust

28. Find the Index of the First Occurrence in a String

Tags: Two Pointers String String Matching
Code: C# Go Python Rust

30. Substring with Concatenation of All Words

Tags: Hash Table String Sliding Window
Code: C#

31. Next Permutation

Tags: Array Two Pointers
Code: C# Go Python

32. Longest Valid Parentheses

Tags: String Dynamic Programming Stack
Code: C# Go Python

33. Search in Rotated Sorted Array

Tags: Array Binary Search
Code: C#

34. Find First and Last Position of Element in Sorted Array

Tags: Array Binary Search
Code: C# Go Python

35. Search Insert Position

Tags: Array Binary Search
Code: C#

36. Valid Sudoku

Tags: Array Hash Table Matrix
Code: C# Go

39. Combination Sum

Tags: Array Backtracking
Code: C#

41. First Missing Positive

Tags: Array Hash Table
Code: C# Go Python

42. Trapping Rain Water

Tags: Array Two Pointers Dynamic Programming Stack Monotonic Stack
Code: C# Go Python Rust

43. Multiply Strings

Tags: Math String Simulation
Code: C#

45. Jump Game II

Tags: Array Dynamic Programming Greedy
Code: C# Go Python

46. Permutations

Tags: Array Backtracking
Code: C#

48. Rotate Image

Tags: Array Math Matrix
Code: C# Python

49. Group Anagrams

Tags: Array Hash Table String Sorting
Code: C# Go

50. Pow(x, n)

Tags: Math Recursion
Code: C# Go Python

51. N-Queens

Tags: Array Backtracking
Code: C# Go Python

52. N-Queens II

Tags: Backtracking
Code: C# Go Python Rust

53. Maximum Subarray

Tags: Array Divide and Conquer Dynamic Programming
Code: C# Go

54. Spiral Matrix

Tags: Array Matrix Simulation
Code: C#

55. Jump Game

Tags: Array Dynamic Programming Greedy
Code: C# Go Python Rust

56. Merge Intervals

Tags: Array Sorting
Code: C#

57. Insert Interval

Tags: Array
Code: C#

58. Length of Last Word

Tags: String
Code: C# Go Python Rust

59. Spiral Matrix II

Tags: Array Matrix Simulation
Code: C# Python

61. Rotate List

Tags: Linked List Two Pointers
Code: C#

64. Minimum Path Sum

Tags: Array Dynamic Programming Matrix
Code: C# Go Python

66. Plus One

Tags: Array Math
Code: C# Go Python

67. Add Binary

Tags: Math String Bit Manipulation Simulation
Code: C# Go Python

68. Text Justification

Tags: Array String Simulation
Code: C# Go Python

69. Sqrt(x)

Tags: Math Binary Search
Code: C# Go Python

70. Climbing Stairs

Tags: Math Dynamic Programming Memoization
Code: C#

71. Simplify Path

Tags: String Stack
Code: C# Go Python Rust

72. Edit Distance

Tags: String Dynamic Programming
Code: C# Go Python

73. Set Matrix Zeroes

Tags: Array Hash Table Matrix
Code: C# Python

74. Search a 2D Matrix

Tags: Array Binary Search Matrix
Code: C#

75. Sort Colors

Tags: Array Two Pointers Sorting
Code: C#

76. Minimum Window Substring

Tags: Hash Table String Sliding Window
Code: C# Go Python

77. Combinations

Tags: Backtracking
Code: C#

78. Subsets

Tags: Array Backtracking Bit Manipulation
Code: C# Go Python

79. Word Search

Tags: Array Backtracking Matrix
Code: C#

80. Remove Duplicates from Sorted Array II

Tags: Array Two Pointers
Code: C# Go Python Rust

82. Remove Duplicates from Sorted List II

Tags: Linked List Two Pointers
Code: C# Python

83. Remove Duplicates from Sorted List

Tags: Linked List
Code: C#

84. Largest Rectangle in Histogram

Tags: Array Stack Monotonic Stack
Code: C# Python

86. Partition List

Tags: Linked List Two Pointers
Code: C#

88. Merge Sorted Array

Tags: Array Two Pointers Sorting
Code: C# Go Python

90. Subsets II

Tags: Array Backtracking Bit Manipulation
Code: C# Go Python

91. Decode Ways

Tags: String Dynamic Programming
Code: C# Go Python

92. Reverse Linked List II

Tags: Linked List
Code: C#

93. Restore IP Addresses

Tags: String Backtracking
Code: C#

94. Binary Tree Inorder Traversal

Tags: Stack Tree Depth-First Search Binary Tree
Code: C# Go Python

98. Validate Binary Search Tree

Tags: Tree Depth-First Search Binary Search Tree Binary Tree
Code: C#

100. Same Tree

Tags: Tree Depth-First Search Breadth-First Search Binary Tree
Code: C#

101. Symmetric Tree

Tags: Tree Depth-First Search Breadth-First Search Binary Tree
Code: C#

102. Binary Tree Level Order Traversal

Tags: Tree Breadth-First Search Binary Tree
Code: C#

103. Binary Tree Zigzag Level Order Traversal

Tags: Tree Breadth-First Search Binary Tree
Code: C# Python

104. Maximum Depth of Binary Tree

Tags: Tree Depth-First Search Breadth-First Search Binary Tree
Code: C# Go Python

105. Construct Binary Tree from Preorder and Inorder Traversal

Tags: Array Hash Table Divide and Conquer Tree Binary Tree
Code: C#

106. Construct Binary Tree from Inorder and Postorder Traversal

Tags: Array Hash Table Divide and Conquer Tree Binary Tree
Code: C#

108. Convert Sorted Array to Binary Search Tree

Tags: Array Divide and Conquer Tree Binary Search Tree Binary Tree
Code: C#

110. Balanced Binary Tree

Tags: Tree Depth-First Search Binary Tree
Code: C#

112. Path Sum

Tags: Tree Depth-First Search Breadth-First Search Binary Tree
Code: C#

113. Path Sum II

Tags: Backtracking Tree Depth-First Search Binary Tree
Code: C# Python

114. Flatten Binary Tree to Linked List

Tags: Linked List Stack Tree Depth-First Search Binary Tree
Code: C# Go Python

116. Populating Next Right Pointers in Each Node

Tags: Linked List Tree Depth-First Search Breadth-First Search Binary Tree
Code: C#

117. Populating Next Right Pointers in Each Node II

Tags: Linked List Tree Depth-First Search Breadth-First Search Binary Tree
Code: C#

118. Pascal's Triangle

Tags: Array Dynamic Programming
Code: C#

119. Pascal's Triangle II

Tags: Array Dynamic Programming
Code: C# Python

120. Triangle

Tags: Array Dynamic Programming
Code: C#

121. Best Time to Buy and Sell Stock

Tags: Array Dynamic Programming
Code: C# Go Python Rust

122. Best Time to Buy and Sell Stock II

Tags: Array Dynamic Programming Greedy
Code: C# Go Python Rust

124. Binary Tree Maximum Path Sum

Tags: Dynamic Programming Tree Depth-First Search Binary Tree
Code: C# Go Python

125. Valid Palindrome

Tags: Two Pointers String
Code: C# Go Python Rust

128. Longest Consecutive Sequence

Tags: Array Hash Table Union Find
Code: C# Go

129. Sum Root to Leaf Numbers

Tags: Tree Depth-First Search Binary Tree
Code: C# Go Python

130. Surrounded Regions

Tags: Array Depth-First Search Breadth-First Search Union Find Matrix
Code: C# Go Python

131. Palindrome Partitioning

Tags: String Dynamic Programming Backtracking
Code: C#

133. Clone Graph

Tags: Hash Table Depth-First Search Breadth-First Search Graph
Code: C# Python

134. Gas Station

Tags: Array Greedy
Code: C# Go Python Rust

135. Candy

Tags: Array Greedy
Code: C# Go Python Rust

136. Single Number

Tags: Array Bit Manipulation
Code: C#

137. Single Number II

Tags: Array Bit Manipulation
Code: C#

138. Copy List with Random Pointer

Tags: Hash Table Linked List
Code: C# Python

139. Word Break

Tags: Array Hash Table String Dynamic Programming Trie Memoization
Code: C# Python

141. Linked List Cycle

Tags: Hash Table Linked List Two Pointers
Code: C# Go Python

142. Linked List Cycle II

Tags: Hash Table Linked List Two Pointers
Code: C# Go

143. Reorder List

Tags: Linked List Two Pointers Stack Recursion
Code: C# Go Python

144. Binary Tree Preorder Traversal

Tags: Stack Tree Depth-First Search Binary Tree
Code: C#

145. Binary Tree Postorder Traversal

Tags: Stack Tree Depth-First Search Binary Tree
Code: C#

146. LRU Cache

Tags: Hash Table Linked List Design Doubly-Linked List
Code: C#

148. Sort List

Tags: Linked List Two Pointers Divide and Conquer Sorting Merge Sort
Code: C#

150. Evaluate Reverse Polish Notation

Tags: Array Math Stack
Code: C# Go

151. Reverse Words in a String

Tags: Two Pointers String
Code: C# Go Python

152. Maximum Product Subarray

Tags: Array Dynamic Programming
Code: C# Python

153. Find Minimum in Rotated Sorted Array

Tags: Array Binary Search
Code: C# Go Python

155. Min Stack

Tags: Stack Design
Code: C#

160. Intersection of Two Linked Lists

Tags: Hash Table Linked List Two Pointers
Code: C# Python

162. Find Peak Element

Tags: Array Binary Search
Code: C# Go Python

167. Two Sum II - Input Array Is Sorted

Tags: Array Two Pointers Binary Search
Code: C# Go

169. Majority Element

Tags: Array Hash Table Divide and Conquer Sorting Counting
Code: C# Go Python Rust

173. Binary Search Tree Iterator

Tags: Stack Tree Design Binary Search Tree Binary Tree Iterator
Code: C#

176. Second Highest Salary

Tags: Database
Code: SQL

180. Consecutive Numbers

Tags: Database
Code: SQL

185. Department Top Three Salaries

Tags: Database
Code: SQL

187. Repeated DNA Sequences

Tags: Hash Table String Bit Manipulation Sliding Window Rolling Hash Hash Function
Code: C#

189. Rotate Array

Tags: Array Math Two Pointers
Code: C# Go Python

190. Reverse Bits

Tags: Divide and Conquer Bit Manipulation
Code: C#

191. Number of 1 Bits

Tags: Divide and Conquer Bit Manipulation
Code: C#

196. Delete Duplicate Emails

Tags: Database
Code: SQL

197. Rising Temperature

Tags: Database
Code: SQL

198. House Robber

Tags: Array Dynamic Programming
Code: C# Python

199. Binary Tree Right Side View

Tags: Tree Depth-First Search Breadth-First Search Binary Tree
Code: C#

200. Number of Islands

Tags: Array Depth-First Search Breadth-First Search Union Find Matrix
Code: C#

202. Happy Number

Tags: Hash Table Math Two Pointers
Code: C#

203. Remove Linked List Elements

Tags: Linked List Recursion
Code: C# Go Python

205. Isomorphic Strings

Tags: Hash Table String
Code: C# Go

206. Reverse Linked List

Tags: Linked List Recursion
Code: C# Go Python

207. Course Schedule

Tags: Depth-First Search Breadth-First Search Graph Topological Sort
Code: C# Python

208. Implement Trie (Prefix Tree)

Tags: Hash Table String Design Trie
Code: C#

209. Minimum Size Subarray Sum

Tags: Array Binary Search Sliding Window Prefix Sum
Code: C# Go Python Rust

210. Course Schedule II

Tags: Depth-First Search Breadth-First Search Graph Topological Sort
Code: C#

211. Design Add and Search Words Data Structure

Tags: String Depth-First Search Design Trie
Code: C#

212. Word Search II

Tags: Array String Backtracking Trie Matrix
Code: C#

213. House Robber II

Tags: Array Dynamic Programming
Code: C# Python

215. Kth Largest Element in an Array

Tags: Array Divide and Conquer Sorting Heap (Priority Queue) Quickselect
Code: C# Pyhton

216. Combination Sum III

Tags: Array Backtracking
Code: C# Go Python

217. Contains Duplicate

Tags: Array Hash Table Sorting
Code: C# Go

219. Contains Duplicate II

Tags: Array Hash Table Sliding Window
Code: C# Go Python Rust

222. Count Complete Tree Nodes

Tags: Binary Search Bit Manipulation Tree Binary Tree
Code: C# Go Python

224. Basic Calculator

Tags: Math String Stack Recursion
Code: C# Go Python Rust

226. Invert Binary Tree

Tags: Tree Depth-First Search Breadth-First Search Binary Tree
Code: C#

227. Basic Calculator II

Tags: Math String Stack
Code: C#

228. Summary Ranges

Tags: Array
Code: C# Go Python Rust

230. Kth Smallest Element in a BST

Tags: Tree Depth-First Search Binary Search Tree Binary Tree
Code: C#

231. Power of Two

Tags: Math Bit Manipulation Recursion
Code: C#

232. Implement Queue using Stacks

Tags: Stack Design Queue
Code: C#

234. Palindrome Linked List

Tags: Linked List Two Pointers Stack Recursion
Code: C#

235. Lowest Common Ancestor of a Binary Search Tree

Tags: Tree Depth-First Search Binary Search Tree Binary Tree
Code: C# Python

236. Lowest Common Ancestor of a Binary Tree

Tags: Tree Depth-First Search Binary Tree
Code: C# Python

238. Product of Array Except Self

Tags: Array Prefix Sum
Code: C# Go

239. Sliding Window Maximum

Tags: Array Queue Sliding Window Heap (Priority Queue) Monotonic Queue
Code: C# Python

240. Search a 2D Matrix II

Tags: Array Binary Search Divide and Conquer Matrix
Code: C# Python

242. Valid Anagram

Tags: Hash Table String Sorting
Code: C# Go Python Rust

268. Missing Number

Tags: Array Hash Table Math Binary Search Bit Manipulation Sorting
Code: C# Python

274. H-Index

Tags: Array Sorting Counting Sort
Code: C# Go Python

278. First Bad Version

Tags: Binary Search Interactive
Code: C#

279. Perfect Squares

Tags: Math Dynamic Programming Breadth-First Search
Code: C# Go Python

283. Move Zeroes

Tags: Array Two Pointers
Code: C#

287. Find the Duplicate Number

Tags: Array Two Pointers Binary Search Bit Manipulation
Code: C# Python

289. Game of Life

Tags: Array Matrix Simulation
Code: C# Go Python Rust

290. Word Pattern

Tags: Hash Table String
Code: C# Python

295. Find Median from Data Stream

Tags: Two Pointers Design Sorting Heap (Priority Queue) Data Stream
Code: C#

297. Serialize and Deserialize Binary Tree

Tags: String Tree Depth-First Search Breadth-First Search Design Binary Tree
Code: C#

299. Bulls and Cows

Tags: Hash Table String Counting
Code: C#

300. Longest Increasing Subsequence

Tags: Array Binary Search Dynamic Programming
Code: C# Python

322. Coin Change

Tags: Array Dynamic Programming Breadth-First Search
Code: C#

328. Odd Even Linked List

Tags: Linked List
Code: C#

334. Increasing Triplet Subsequence

Tags: Array Greedy
Code: C# Python

338. Counting Bits

Tags: Dynamic Programming Bit Manipulation
Code: C# Python

344. Reverse String

Tags: Two Pointers String
Code: C#

345. Reverse Vowels of a String

Tags: Two Pointers String
Code: C# Go Python

347. Top K Frequent Elements

Tags: Array Hash Table Divide and Conquer Sorting Heap (Priority Queue) Bucket Sort Counting Quickselect
Code: C# Go

350. Intersection of Two Arrays II

Tags: Array Hash Table Two Pointers Binary Search Sorting
Code: C#

355. Design Twitter

Tags: Hash Table Linked List Designm Heap (Priority Queue)
Code: C#

371. Sum of Two Integers

Tags: Math Bit Manipulation
Code: C#

374. Guess Number Higher or Lower

Tags: Binary Search Interactive
Code: C# Go Python

380. Insert Delete GetRandom O(1)

Tags: Array Hash Table Math Design Randomized
Code: C#

383. Ransom Note

Tags: Hash Table String Counting
Code: C#

387. First Unique Character in a String

Tags: Hash Table String Queue Counting
Code: C#

392. Is Subsequence

Tags: Two Pointers String Dynamic Programming
Code: C# Go Python Rust

394. Decode String

Tags: String Stack Recursion
Code: C#

399. Evaluate Division

Tags: Array Depth-First Search Breadth-First Search Union Find Graph Shortest Path
Code: C# Go Python

409. Longest Palindrome

Tags: Hash Table String Greedy
Code: C# Go

412. Fizz Buzz

Tags: Math String Simulation
Code: C#

415. Add Strings

Tags: Math String Simulation
Code: C# Python

416. Partition Equal Subset Sum

Tags: Array Dynamic Programming
Code: C# Python

417. Pacific Atlantic Water Flow

Tags: Array Depth-First Search Breadth-First Search Matrix
Code: C#

424. Longest Repeating Character Replacement

Tags: Hash Table String Sliding Window
Code: C#

435. Non-overlapping Intervals

Tags: Array Dynamic Programming Greedy Sorting
Code: C# Python

437. Path Sum III

Tags: Tree Depth-First Search Binary Tree
Code: C#

438. Find All Anagrams in a String

Tags: Hash Table String Sliding Window
Code: C#

443. String Compression

Tags: Two Pointers String
Code: C# Go Python

450. Delete Node in a BST

Tags: Tree Binary Search Tree Binary Tree
Code: C# Python

451. Sort Characters By Frequency

Tags: Hash Table String Sorting Heap (Priority Queue) Bucket Sort Counting
Code: C# Python

452. Minimum Number of Arrows to Burst Balloons

Tags: Array Greedy Sorting
Code: C# Go Python

455. Assign Cookies

Tags: Array Two Pointers Greedy Sorting
Code: C# Go Python

491. Non-decreasing Subsequences

Tags: Array Hash Table Backtracking Bit Manipulation
Code: C#

509. Fibonacci Number

Tags: Math Dynamic Programming Recursion Memoization
Code: C#

530. Minimum Absolute Difference in BST

Tags: Tree Depth-First Search Breadth-First Search Binary Search Tree Binary Tree
Code: C# Go Python

542. 01 Matrix

Tags: Array Dynamic Programming Breadth-First Search Matrix
Code: C#

543. Diameter of Binary Tree

Tags: Tree Depth-First Search Binary Tree
Code: C#

547. Number of Provinces

Tags: Depth-First Search Breadth-First Search Union Find Graph
Code: C#

550. Game Play Analysis IV

Tags: Database
Code: SQL

557. Reverse Words in a String III

Tags: Two Pointers String
Code: C#

560. Subarray Sum Equals K

Tags: Array Hash Table Prefix Sum
Code: C# Python

566. Reshape the Matrix

Tags: Array Matrix Simulation
Code: C#

567. Permutation in String

Tags: Hash Table Two Pointers String Sliding Window
Code: C#

570. Managers with at Least 5 Direct Reports

Tags: Database
Code: SQL

572. Subtree of Another Tree

Tags: Tree Depth-First Search String Matching Binary Tree Hash Function
Code: C# Go Python

577. Employee Bonus

Tags: Database
Code: SQL

584. Find Customer Referee

Tags: Database
Code: SQL

585. Investments in 2016

Tags: Database
Code: SQL

589. N-ary Tree Preorder Traversal

Tags: Stack Tree Depth-First Search
Code: C# Python

595. Big Countries

Tags: Database
Code: SQL

596. Classes More Than 5 Students

Tags: Database
Code: SQL

602. Friend Requests II: Who Has the Most Friends

Tags: Database
Code: SQL

605. Can Place Flowers

Tags: Array Greedy
Code: C# Go Python

606. Construct String from Binary Tree

Tags: String Tree Depth-First Search Binary Tree
Code: C# Go Python

610. Triangle Judgement

Tags: Database
Code: SQL

617. Merge Two Binary Trees

Tags: Tree Depth-First Search Breadth-First Search Binary Tree
Code: C#

626. Exchange Seats

Tags: Database
Code: SQL

653. Two Sum IV - Input is a BST

Tags: Hash Table Two Pointers Tree Depth-First Search Breadth-First Search Binary Search Tree Binary Tree
Code: C#

619. Biggest Single Number

Tags: Database
Code: SQL

620. Not Boring Movies

Tags: Database
Code: SQL

621. Task Scheduler

Tags: Array Hash Table Greedy Sorting Heap (Priority Queue) Counting
Code: C#

637. Average of Levels in Binary Tree

Tags: Tree Depth-First Search Breadth-First Search Binary Tree
Code: C# Go Python

643. Maximum Average Subarray I

Tags: Array Sliding Window
Code: C# Go Python

647. Palindromic Substrings

Tags: String Dynamic Programming
Code: C# Python

649. Dota2 Senate

Tags: String Greedy Queue
Code: C# Go Python

661. Image Smoother

Tags: Array Matrix
Code: C# Go Python Rust

692. Top K Frequent Words

Tags: Hash Table String Trie Sorting Heap (Priority Queue) Bucket Sort Counting
Code: C#

695. Max Area of Island

Tags: Array Depth-First Search Breadth-First Search Union Find Matrix
Code: C#

700. Search in a Binary Search Tree

Tags: Tree Binary Search Tree Binary Tree
Code: C#

701. Insert into a Binary Search Tree

Tags: Tree Binary Search Tree Binary Tree
Code: C#

703. Kth Largest Element in a Stream

Tags: Tree Design Binary Search Tree Heap (Priority Queue) Binary Tree Data Stream
Code: C#

704. Binary Search

Tags: Array Binary Search
Code: C#

706. Design HashMap

Tags: Array Hash Table Linked List Design Hash Function
Code: C#

707. Design Linked List

Tags: Linked List Design
Code: C#

714. Best Time to Buy and Sell Stock with Transaction Fee

Tags: Array Dynamic Programming Greedy
Code: C# Go Python Rust

724. Find Pivot Index

Tags: Array Prefix Sum
Code: C# Go

733. Flood Fill

Tags: Array Depth-First Search Breadth-First Search Matrix
Code: C#

735. Asteroid Collision

Tags: Array Stack
Code: C# Go

739. Daily Temperatures

Tags: Array Stack Monotonic Stack
Code: C# Python

746. Min Cost Climbing Stairs

Tags: Array Dynamic Programming
Code: C#

763. Partition Labels

Tags: Hash Table Two Pointers String Greedy
Code: C# Python

783. Minimum Distance Between BST Nodes

Tags: Tree Depth-First Search Breadth-First Search Binary Search Tree Binary Tree
Code: C# Go Python

784. Letter Case Permutation

Tags: String Backtracking Bit Manipulation
Code: C#

790. Domino and Tromino Tiling

Tags: Dynamic Programming
Code: C# Go Python

815. Bus Routes

Tags: Array Hash Table Breadth-First Search
Code: C# Python

841. Keys and Rooms

Tags: Depth-First Search Breadth-First Search Graph
Code: C# Python

844. Backspace String Compare

Tags: Two Pointers String Stack Simulation
Code: C#

853. Car Fleet

Tags: Array Stack Sorting Monotonic Stack
Code: C# Python

867. Transpose Matrix

Tags: Array Matrix Simulation
Code: C# Go Python

872. Leaf-Similar Trees

Tags: Tree Depth-First Search Binary Tree
Code: C# Go Python

875. Koko Eating Bananas

Tags: Array Binary Search
Code: C# Python

876. Middle of the Linked List

Tags: Linked List Two Pointers
Code: C# Go

901. Online Stock Span

Tags: Stack Design Monotonic Stack Data Stream
Code: C#

909. Snakes and Ladders

Tags: Array Breadth-First Search Matrix
Code: C# Go Python

926. Flip String to Monotone Increasing

Tags: String Dynamic Programming
Code: C#

933. Number of Recent Calls

Tags: Design Queue Data Stream
Code: C#

947. Most Stones Removed with Same Row or Column

Tags: Depth-First Search Union Find Graph
Code: C#

973. K Closest Points to Origin

Tags: Array Math Divide and Conquer Geometry Sorting Heap (Priority Queue) Quickselect
Code: C# Python

974. Subarray Sums Divisible by K

Tags: Array Hash Table Prefix Sum
Code: C#

977. Squares of a Sorted Array

Tags: Array Two Pointers Sorting
Code: C#

981. Time Based Key-Value Store

Tags: Hash Table String Binary Search Design
Code: C#

994. Rotting Oranges

Tags: Array Breadth-First Search Matrix
Code: C#

997. Find the Town Judge

Tags: Array Hash Table Graph
Code: C#

1004. Max Consecutive Ones III

Tags: Array Binary Search Sliding Window Prefix Sum
Code: C# Go Python

1045. Customers Who Bought All Products

Tags: Database
Code: SQL

1046. Last Stone Weight

Tags: Array Heap (Priority Queue)
Code: C#

1068. Product Sales Analysis I

Tags: Database
Code: SQL

1070. Product Sales Analysis III

Tags: Database
Code: SQL

1071. Greatest Common Divisor of Strings

Tags: Math String
Code: C# Go Python

1075. Project Employees I

Tags: Database
Code: SQL

1137. N-th Tribonacci Number

Tags: Math Dynamic Programming Memoization
Code: C# Go Python

1141. User Activity for the Past 30 Days I

Tags: Database
Code: SQL

1143. Longest Common Subsequence

Tags: String Dynamic Programming
Code: C# Python

1148. Article Views I

Tags: Database
Code: SQL

1155. Number of Dice Rolls With Target Sum

Tags: Dynamic Programming
Code: C#

1160. Find Words That Can Be Formed by Characters

Tags: Array Hash Table String
Code: C# Go Python

1161. Maximum Level Sum of a Binary Tree

Tags: Tree Depth-First Search Breadth-First Search Binary Tree
Code: C# Go Python

1164. Product Price at a Given Date

Tags: Database
Code: SQL

1174. Immediate Food Delivery II

Tags: Database
Code: SQL

1193. Monthly Transactions I

Tags: Database
Code: SQL

1204. Last Person to Fit in the Bus

Tags: Database
Code: SQL

1207. Unique Number of Occurrences

Tags: Array Hash Table
Code: C# Go Python

1211. Queries Quality and Percentage

Tags: Database
Code: SQL

1235. Maximum Profit in Job Scheduling

Tags: Array Binary Search Dynamic Programming Sorting
Code: C#

1249. Minimum Remove to Make Valid Parentheses

Tags: Array Heap (Priority Queue)
Code: C#

1251. Average Selling Price

Tags: Database
Code: SQL

1266. Minimum Time Visiting All Points

Tags: Array Math Geometry
Code: C# Go Python

1268. Search Suggestions System

Tags: Array String Binary Search Trie Sorting Heap (Priority Queue)
Code: C# Go Python

1280. Students and Examinations

Tags: Database
Code: SQL

1287. Element Appearing More Than 25% In Sorted Array

Tags: Array
Code: C# Go Python Rust

1318. Minimum Flips to Make a OR b Equal to c

Tags: Bit Manipulation
Code: C# Go Python

1321. Restaurant Growth

Tags: Database
Code: SQL

1327. List the Products Ordered in a Period

Tags: Database
Code: SQL

1335. Minimum Difficulty of a Job Schedule

Tags: Array Dynamic Programming
Code: C#

1341. Movie Rating

Tags: Database
Code: SQL

1342. Number of Steps to Reduce a Number to Zero

Tags: String Stack
Code: C# Python

1372. Longest ZigZag Path in a Binary Tree

Tags: Dynamic Programming Tree Depth-First Search Binary Tree
Code: C# Go Python

1378. Replace Employee ID With The Unique Identifier

Tags: Database
Code: SQL

1422. Maximum Score After Splitting a String

Tags: String
Code: C# Go Python Rust

1431. Kids With the Greatest Number of Candies

Tags: Array
Code: C# Go Python

1436. Destination City

Tags: Hash Table String
Code: C# Go Python Rust

1443. Minimum Time to Collect All Apples in a Tree

Tags: Hash Table Tree Depth-First Search Breadth-First Search
Code: C#

1448. Count Good Nodes in Binary Tree

Tags: Tree Depth-First Search Breadth-First Search Binary Tree
Code: C# Python

1456. Maximum Number of Vowels in a Substring of Given Length

Tags: String Sliding Window
Code: C# Go Python

1464. Maximum Product of Two Elements in an Array

Tags: Array Sorting Heap (Priority Queue)
Code: C# Go Python Rust

1466. Reorder Routes to Make All Paths Lead to the City Zero

Tags: Depth-First Search Breadth-First Search Graph
Code: C# Go Python

1472. Design Browser History

Tags: Array Linked List Stack Design Doubly-Linked List Data Stream
Code: C#

1480. Running Sum of 1d Array

Tags: Array Prefix Sum
Code: C# Go

1484. Group Sold Products By The Date

Tags: Database
Code: SQL

1493. Longest Subarray of 1's After Deleting One Element

Tags: Array Dynamic Programming Sliding Window
Code: C# Go Python

1496. Path Crossing

Tags: Hash Table String
Code: C# Go Python

1517. Find Users With Valid E-Mails

Tags: Database
Code: SQL

1527. Patients With a Condition

Tags: Database
Code: SQL

1531. String Compression II

Tags: String Dynamic Programming
Code: C#

1557. Minimum Number of Vertices to Reach All Nodes

Tags: Graph
Code: C# Python

1578. Minimum Time to Make Rope Colorful

Tags: Array String Dynamic Programming Greedy
Code: C# Go Python

1581. Customer Who Visited but Did Not Make Any Transactions

Tags: Database
Code: SQL

1582. Special Positions in a Binary Matrix

Tags: Array Matrix
Code: C# Go Python Rust

1624. Largest Substring Between Two Equal Characters

Tags: Hash Table String
Code: C# Go Python

1633. Percentage of Users Attended a Contest

Tags: Database
Code: SQL

1637. Widest Vertical Area Between Two Points Containing No Points

Tags: Array Sorting
Code: C# Go Python Rust

1657. Determine if Two Strings Are Close

Tags: Hash Table String Sorting
Code: C# Go Python

1661. Average Time of Process per Machine

Tags: Database
Code: SQL

1662. Check If Two String Arrays are Equivalent

Tags: Array String
Code: C# Go Python

1667. Fix Names in a Table

Tags: Database
Code: SQL

1672. Richest Customer Wealth

Tags: Array Matrix
Code: C#

1679. Max Number of K-Sum Pairs

Tags: Array Hash Table Two Pointers Sorting
Code: C# Go Python

1683. Invalid Tweets

Tags: Database
Code: SQL

1688. Count of Matches in Tournament

Tags: Math Simulation
Code: C# Go Python Rust

1706. Where Will the Ball Fall

Tags: Array Matrix
Code: C#

1716. Calculate Money in Leetcode Bank

Tags: Math
Code: C# Go Python Rust

1731. The Number of Employees Which Report to Each Employee

Tags: Database
Code: SQL

1732. Find the Highest Altitude

Tags: Array Prefix Sum
Code: C# Go Python

1729. Find Followers Count

Tags: Database
Code: SQL

1757. Recyclable and Low Fat Products

Tags: Database
Code: SQL

1758. Minimum Changes To Make Alternating Binary String

Tags: String
Code: C# Go Python

1768. Merge Strings Alternately

Tags: Two Pointers String
Code: C# Go Python

1789. Primary Department for Each Employee

Tags: Database
Code: SQL

1823. Find the Winner of the Circular Game

Tags: Array Math Recursion Queue Simulation
Code: C# Python

1897. Redistribute Characters to Make All Strings Equal

Tags: Hash Table String Counting
Code: C# Go Python

1903. Largest Odd Number in String

Tags: Math String Greedy
Code: C# Go Python Rust

1907. Count Salary Categories

Tags: Database
Code: SQL

1913. Maximum Product Difference Between Two Pairs

Tags: Array Sorting
Code: C# Go Python Rust

1926. Nearest Exit from Entrance in Maze

Tags: Array Breadth-First Search Matrix
Code: C# Go Python

1934. Confirmation Rate

Tags: Database
Code: SQL

1978. Employees Whose Manager Left the Company

Tags: Database
Code: SQL

1991. Find the Middle Index in Array

Tags: Array Prefix Sum
Code: C#

2095. Delete the Middle Node of a Linked List

Tags: Linked List Two Pointers
Code: C# Go Python

2125. Number of Laser Beams in a Bank

Tags: Array Math String Matrix
Code: C# Go Python

2130. Maximum Twin Sum of a Linked List

Tags: Linked List Two Pointers Stack
Code: C# Go Python

2131. Longest Palindrome by Concatenating Two Letter Words

Tags: Array Hash Table String Greedy Counting
Code: C#

2215. Find the Difference of Two Arrays

Tags: Array Hash Table
Code: C# Go Python

2235. Add Two Integers

Tags: Math
Code: C# Go

2244. Minimum Rounds to Complete All Tasks

Tags: Array Hash Table Greedy Counting
Code: C# Go Python

2264. Largest 3-Same-Digit Number in String

Tags: String
Code: C# Go Python Rust

2300. Successful Pairs of Spells and Potions

Tags: Array Two Pointers Binary Search Sorting
Code: C# Go Python

2336. Smallest Number in Infinite Set

Tags: Hash Table Design Heap (Priority Queue)
Code: C#

2352. Equal Row and Column Pairs

Tags: Array Hash Table Matrix Simulation
Code: C# Go Python

2353. Design a Food Rating System

Tags: Hash Table Design Heap (Priority Queue) Ordered Set
Code: C#

2356. Number of Unique Subjects Taught by Each Teacher

Tags: Database
Code: SQL

2390. Removing Stars From a String

Tags: String Stack Simulation
Code: C# Go Python

2462. Total Cost to Hire K Workers

Tags: Array Two Pointers Heap (Priority Queue) Simulation
Code: C#

2482. Difference Between Ones and Zeros in Row and Column

Tags: Array Matrix Simulation
Code: C# Go Python Rust

2542. Maximum Subsequence Score

Tags: Array Greedy Sorting Heap (Priority Queue)
Code: C# Go Python

2610. Convert an Array Into a 2D Array With Conditions

Tags: Array Hash Table
Code: C#

2620. Counter

Tags:
Code: TypeScript JavaScript

2665. Counter II

Tags:
Code: TypeScript JavaScript

2667. Create Hello World Function

Tags:
Code: TypeScript JavaScript

2704. To Be Or Not To Be

Tags:
Code: TypeScript JavaScript

2706. Buy Two Chocolates

Tags: Array Sorting
Code: C# Go Python Rust

2870. Minimum Number of Operations to Make Array Empty

Tags: Array Hash Table Greedy Counting
Code: C# Go Python

2877. Create a DataFrame from List

Tags:
Code: Pandas

2878. Get the Size of a DataFrame

Tags:
Code: Pandas

2879. Display the First Three Rows

Tags:
Code: Pandas

2880. Select Data

Tags:
Code: Pandas

2881. Create a New Column

Tags:
Code: Pandas

2882. Drop Duplicate Rows

Tags:
Code: Pandas

2883. Drop Missing Data

Tags:
Code: Pandas

2884. Modify Columns

Tags:
Code: Pandas

2885. Rename Columns

Tags:
Code: Pandas

2886. Change Data Type

Tags:
Code: Pandas

2887. Fill Missing Data

Tags:
Code: Pandas

2888. Reshape Data: Concatenate

Tags:
Code: Pandas

2889. Reshape Data: Pivot

Tags:
Code: Pandas

2890. Reshape Data: Melt

Tags:
Code: Pandas

2891. Method Chaining

Tags:
Code: Pandas