rodonal/leetcode-scala-3

LeetCode Solutions in Scala 3

LeetCode-Scala-3

Solutions of selected LeetCode problems in Scala 3.

Goal

• Learn Scala 3 :)
• Practise Algorithm :)

Code

• Try to be compact and readable at the same time
• Try Scala 3 syntax and features but with less Scala specific libraries

Solutions

• Solutions are organized into topics, following the same list as LeetCode
• Topics are further divided into category based on use cases
• Solutions in each Topic/Category are ordered by difficulty level
• Solutions required explanation and attention are bold

Topic	Category	Problem List
Hashmap	Check existence with O(1)	1. Two Sum 387. First unique character in a string 202. Happy Number
	Discrete key/value container for further processing	205. Isomorphic Strings 299. Bulls and Cows 554. Brick Wall
	Implementation and other usages	380. Insert Delete GetRandom O(1)
OrderedSet	Get a key based on predefined order	729. My Calendar I 731. My Calendar II 1818. Minimum Absolute Sum Difference
	A compact ordered container	732. My Calendar III 855. Exam Room
LinkedList	Basic operation	61. Rotate List 206. Reverse Linked List 143. Reorder List 86. Partition List
	Additional operation	19. Remove Nth Node From End of List 83. Remove Duplicates from Sorted List 82. Remove Duplicates from Sorted List II 138. Copy List with Random Pointer
	Use of linked list	2. Add Two Numbers 445. Add Two Numbers 2
	Others	160. Intersection of Two Linked Lists
Two Pointers		3. Longest Substring Without Repeating Characters 11. Container With Most Water 16. 3Sum Closest 209. Minimum Size Sub array Sum 42. Trapping Rain Water 15. 3Sum 28. Implement strStr() 75. Sort Colors 80. Remove Duplicates from Sorted Array II 167. Two Sum II 159. Longest Substring with At Most Two Distinct Characters 228. Summary Ranges 443. String Compression 219. Contains Duplicate II
Fast Slow Pointers		141. Linked List Cycle 876. Middle of the Linked List 142. Linked List Cycle II
String		6. ZigZag Conversion 14. Longest Common Prefix 763. Partition Labels 161. One Edit Distance 165. Compare Version Numbers 30. Substring with Concatenation of All Words 76. Minimum Window Substring 415. Add Strings 67. Add Binary 38. Count and Say
Tries		208. Implement Tries 139. Word Break 140. Word Break 2 212. Word Search 2 1065. Index Pairs of a String
Number		7. Reverse Integer 9. Palindrome Number 43. Multiply Strings
Counting		169. Majority ElementM 229. Majority Element 2 358. Rearrange String k Distance Apart 383. Ransom Note
Math		12. Integer to Roman 13. Roman to Integer 66. Plus One 50. Pow(x, n) 96. Unique Binary Search Trees 149. Max Points on a Line 166. Fraction to Recurring Decimal 172. Factorial Trailing Zeroes 168. Excel Sheet Column Title 171. Excel Sheet Column Number
Bit		405. Convert a Number to Hexadecimal 29. Divide Two Integers 78. Subsets 89. Gray Code 136. Single Number 137. Single Number 2 187. Repeated DNA 190. Reverse Bits 191. Number of 1 Bits
Array		26. Remove Duplicates from Sorted Array 88. Merge Sorted Array 78. Subsets 945. Minimum Increment to Make Array Unique 121. Best Time to Buy and Sell Stock 125. Valid Palindrome 151. Reverse Words in a String 189. Rotate Array 680. Valid Palindrome II 283. Move Zeroes
Matrix		54. Spiral Matrix 36. Valid Sudoku 37. Sudoku Solver 48. Rotate Image 59. Spiral Matrix II 73. Set Matrix Zero 74. Search a 2D Matrix
Prefix Sum		238. Product of Array Except Self 303. Range Sum Query - Immutable 724. Find Pivot Index 536. Continuous Subarray Sum 525. Contiguous Array
Stack		155. Min Stack 20. Valid Parentheses 901. Online Stock Span 581. Shortest Unsorted Continuous Sub array 150. Evaluate Reverse Polish Notation 32. Longest Valid Parentheses 71. Simplify Path 84. Largest Rectangle in Histogram 394. Decode String
Queue		225. Implement Stack using Queues 232. Implement Queue Using Stacks 239. Sliding Window Maximum 649. Dota2 Senate 281. Zigzag Iterator 950. Reveal Cards In Increasing Order
Sort		148. Sort List 49. Group Anagrams 56. Merge Intervals
Bucket Sort		347. Top K Frequent Elements 692. Top K Frequent Words 451. Sort Characters By Frequency 220. Contains Duplicate III 164. Maximum Gap
Recursion		21. Merge Two Sorted Lists 24. Swap Nodes in Pairs 25. Reverse Nodes in K-Group 60. Permutation Sequence 23. Merge K Sorted List 247. Strobogrammatic Number II 87. Scramble String
Tree	Tree Traversals	144. Binary Tree Preorder Traversal 94. Binary Tree Inorder Traversal 145. Binary Tree Postorder Traversal 102. Binary Tree Level Order Traversal 103. Binary Tree Zigzag Level Order Traversal
	Other operations	226. Invert Binary Tree
	Check Tree properties	110. Balanced Binary Tree 101. Symmetric Tree 104. Maximum Depth of Binary Tree 111. Minimum Depth of Binary Tree 236. Lowest Common Ancestor of a Binary Tree
	Construction and Destruction of Tree	114. Flatten Binary Tree to Linked List 105. Construct Binary Tree from Preorder and Inorder Traversal 106. Construct Binary Tree from Inorder and Postorder Traversal
Binary Search Tree	Check BST properties	98. Validate Binary Search Tree 100. Same Tree 235. Lowest Common Ancestor of a Binary Search Tree
	Modify BST	450. Delete Node in a BST 701. Insert into a Binary Search Tree
	Construct BST	108. Convert Sorted Array to Binary Search Tree 173. Binary Search Tree Iterator
	Traversal of BST	99. Recover Binary Search Tree 257. Binary Tree Paths
Binary Search		69. Sqrt(x) 34. Find First and Last Position of Element in Sorted Array 33. Search in Rotated Sorted Array 81. Search in Rotated Sorted Array II 153. Find Minimum in Rotated Sorted Array 154. Find Minimum in Rotated Sorted Array II 35. Search Insert Position 278. First Bad Version 4. Median of Two Sorted Arrays 162. Find Peak Element 275. H-Index II
DFS		112. Path Sum 116. Populating Next Right Pointers in Each Node 129. Sum Root to Leaf Numbers 156. Binary Tree upside Down 113. Path Sum II
BFS		127. Word Ladder 130. Surrounded Regions 199. Binary Tree Right Side View 133. Clone Graph
Graph		207. Course Schedule 210. Course Schedule II 310. Minimum Height Trees
Union Find		200. Number of Islands 305. Number of Islands II 547. Number of Provinces
Heap		506. Relative Ranks 264. Ugly Number II 215. Kth Largest Element in an Array 23. Merge K sorted list 218. The Skyline
Back Tracking		22. Generate Parentheses 40. Combination Sum II 46. Permutations 10. Regular Expression Matching 17. Letter Combinations of a Phone Number 47. Permutations II 51. N-Queens 52. N-Queens 2 77. Combinations 79. Word Search 93. Restore IP Addresses
Dynamic Programming		70. Climbing Stairs 64. Minimum Path Sum 53. Maximum Subarray 5. Longest Palindromic Substring 91. Decode Ways 174. Dungeon Game 55. Jump Game 63. Unique Paths 2 97. Interleaving String 115. Distinct Subsequences 120. Triangle 123. Best Time to Buy and Sell Stock III
Greedy		122. Best Time to Buy and Sell Stock II 134. Gas Station 179. Largest Number 44. Wildcard Matching 135. Candy