TypeScript Solutions

🐳 LeetCode of algorithms with JavaScript solutions written in TypeScript.

Usage

1. Clone this project

$ git clone https://github.com/Shyam-Chen/TypeScript-Solutions
$ cd TypeScript-Solutions

2. Install dependencies

$ pnpm install

3. Run tests

$ pnpm test

# run a specific test file
$ pnpm test <FILE_NAME>
# e.g.
$ pnpm test twoSum.test.ts

Beginning - Algorithms

解題前應該學會的思路與技巧

1. 陣列 (Array)
2. 鏈結串列 (Linked List)
3. 堆疊 (Stack)
4. 佇列 (Queue)
5. 雜湊表 (Hash Table)
6. 樹 (Tree)
7. 堆積 (Heap)
8. 圖 (Graph)
9. 字典樹 (Trie)
10. 排序 (Sorting)
11. 搜尋 (Searching)
12. 分治 (Divide and Conquer)
13. 回溯 (Backtracking)
14. 動態規劃 (Dynamic Programming)
15. 貪婪 (Greedy)
16. 位元操作 (Bit Manipulation)

Basic - LeetCode 75

Ace Coding Interview with 75 Qs

• 75 Essential & Trending Problems
• Must-do problem list for interview prep
• Best for 1~3 month of prep time

Problems

Array / String
1768. Merge Strings Alternately	Solution	Easy	詳解
1071. Greatest Common Divisor of Strings	Solution	Easy	詳解
1431. Kids With the Greatest Number of Candies	Solution	Easy	詳解
605. Can Place Flowers	Solution	Easy	詳解
345. Reverse Vowels of a String	Solution	Easy	詳解
151. Reverse Words in a String	Solution	Medium	詳解
238. Product of Array Except Self	Solution	Medium	詳解
334. Increasing Triplet Subsequence	Solution	Medium	詳解
443. String Compression	Solution	Medium	詳解

Two Pointers
283. Move Zeroes	Solution	Easy
392. Is Subsequence	Solution	Easy
11. Container With Most Water	Solution	Medium
1679. Max Number of K-Sum Pairs	Solution	Medium

Sliding Window
643. Maximum Average Subarray I	Solution	Easy
1456. Maximum Number of Vowels in a Substring of Given Length	Solution	Medium
1004. Max Consecutive Ones III	Solution	Medium
1493. Longest Subarray of 1's After Deleting One Element	Solution	Medium

Prefix Sum
1732. Find the Highest Altitude	Solution	Easy
724. Find Pivot Index	Solution	Easy

Hash Map / Set
2215. Find the Difference of Two Arrays	Solution	Easy
1207. Unique Number of Occurrences	Solution	Easy
1657. Determine if Two Strings Are Close	Solution	Medium
2352. Equal Row and Column Pairs	Solution	Medium

Stack
2390. Removing Stars From a String	Solution	Medium
735. Asteroid Collision	Solution	Medium
394. Decode String	Solution	Medium

Queue
933. Number of Recent Calls	Solution	Easy
649. Dota2 Senate	Solution	Medium

Linked List
2095. Delete the Middle Node of a Linked List	Solution	Medium
328. Odd Even Linked List	Solution	Medium
206. Reverse Linked List	Solution	Easy
2130. Maximum Twin Sum of a Linked List	Solution	Medium

Binary Tree - DFS
104. Maximum Depth of Binary Tree	Solution	Easy
872. Leaf-Similar Trees	Solution	Easy
1448. Count Good Nodes in Binary Tree	Solution	Medium
437. Path Sum III	Solution	Medium
1372. Longest ZigZag Path in a Binary Tree	Solution	Medium
236. Lowest Common Ancestor of a Binary Tree	Solution	Medium

Binary Tree - BFS
199. Binary Tree Right Side View	Solution	Medium
1161. Maximum Level Sum of a Binary Tree	Solution	Medium

Binary Search Tree
700. Search in a Binary Search Tree	Solution	Easy
450. Delete Node in a BST	Solution	Medium

Graphs - DFS
841. Keys and Rooms	Solution	Medium
547. Number of Provinces	Solution	Medium
1466. Reorder Routes to Make All Paths Lead to the City Zero	Solution	Medium
399. Evaluate Division	Solution	Medium

Graphs - BFS
1926. Nearest Exit from Entrance in Maze	Solution	Medium
994. Rotting Oranges	Solution	Medium

Heap / Priority Queue
215. Kth Largest Element in an Array	Solution	Medium
2336. Smallest Number in Infinite Set	Solution	Medium
2542. Maximum Subsequence Score	Solution	Medium
2462. Total Cost to Hire K Workers	Solution	Medium

Binary Search
374. Guess Number Higher or Lower	Solution	Easy
2300. Successful Pairs of Spells and Potions	Solution	Medium
162. Find Peak Element	Solution	Medium
875. Koko Eating Bananas	Solution	Medium

Backtracking
17. Letter Combinations of a Phone Number	Solution	Medium
216. Combination Sum III	Solution	Medium

DP - 1D
1137. N-th Tribonacci Number	Solution	Easy
746. Min Cost Climbing Stairs	Solution	Easy
198. House Robber	Solution	Medium
790. Domino and Tromino Tiling	Solution	Medium

DP - Multidimensional
62. Unique Paths	Solution	Medium
1143. Longest Common Subsequence	Solution	Medium
714. Best Time to Buy and Sell Stock with Transaction Fee	Solution	Medium
72. Edit Distance	Solution	Medium

Bit Manipulation
338. Counting Bits	Solution	Easy
136. Single Number	Solution	Easy
1318. Minimum Flips to Make a OR b Equal to c	Solution	Medium

Trie
208. Implement Trie (Prefix Tree)	Solution	Medium
1268. Search Suggestions System	Solution	Medium

Intervals
435. Non-overlapping Intervals	Solution	Medium
452. Minimum Number of Arrows to Burst Balloons	Solution	Medium

Monotonic Stack
739. Daily Temperatures	Solution	Medium
901. Online Stock Span	Solution	Medium

Advanced - Top Interview 150

Must-do List for Interview Prep

• 150 Original & Classic Questions
• Covers comprehensive interview topics
• Best for 3+ months of prep time
• Problems support high-quality editorials

Problems

Array / String
88. Merge Sorted Array	Solution	Easy
27. Remove Element	Solution	Easy
26. Remove Duplicates from Sorted Array	Solution	Easy
80. Remove Duplicates from Sorted Array II	Solution	Medium
169. Majority Element	Solution	Easy
189. Rotate Array	Solution	Medium
121. Best Time to Buy and Sell Stock	Solution	Easy
122. Best Time to Buy and Sell Stock II	Solution	Medium
55. Jump Game	Solution	Medium
45. Jump Game II	Solution	Medium
274. H-Index	Solution	Medium
380. Insert Delete GetRandom O(1)	Solution	Medium
238. Product of Array Except Self	Solution	Medium
134. Gas Station	Solution	Medium
135. Candy	Solution	Hard
42. Trapping Rain Water	Solution	Hard
13. Roman to Integer	Solution	Easy
12. Integer to Roman	Solution	Medium
58. Length of Last Word	Solution	Easy
14. Longest Common Prefix	Solution	Easy
151. Reverse Words in a String	Solution	Medium
6. Zigzag Conversion	Solution	Medium
28. Find the Index of the First Occurrence in a String	Solution	Easy
68. Text Justification	Solution	Hard

Two Pointers
125. Valid Palindrome	Solution	Easy
392. Is Subsequence	Solution	Easy
167. Two Sum II - Input Array Is Sorted	Solution	Medium
11. Container With Most Water	Solution	Medium
15. 3Sum	Solution	Medium

Sliding Window
209. Minimum Size Subarray Sum	Solution	Medium
3. Longest Substring Without Repeating Characters	Solution	Medium
30. Substring with Concatenation of All Words	Solution	Hard
76. Minimum Window Substring	Solution	Hard

Matrix
36. Valid Sudoku	Solution	Medium
54. Spiral Matrix	Solution	Medium
48. Rotate Image	Solution	Medium
73. Set Matrix Zeroes	Solution	Medium
289. Game of Life	Solution	Medium

Hashmap
383. Ransom Note	Solution	Easy
205. Isomorphic Strings	Solution	Easy
290. Word Pattern	Solution	Easy
242. Valid Anagram	Solution	Easy
49. Group Anagrams	Solution	Medium
1. Two Sum	Solution	Easy
202. Happy Number	Solution	Easy
219. Contains Duplicate II	Solution	Easy
128. Longest Consecutive Sequence	Solution	Medium

Intervals
228. Summary Ranges	Solution	Easy
56. Merge Intervals	Solution	Medium
57. Insert Interval	Solution	Medium
452. Minimum Number of Arrows to Burst Balloons	Solution	Medium

Stack
20. Valid Parentheses	Solution	Easy
71. Simplify Path	Solution	Medium
155. Min Stack	Solution	Medium
150. Evaluate Reverse Polish Notation	Solution	Medium
224. Basic Calculator	Solution	Hard

Linked List
141. Linked List Cycle	Solution	Easy
2. Add Two Numbers	Solution	Medium
21. Merge Two Sorted Lists	Solution	Easy
138. Copy List with Random Pointer	Solution	Medium
92. Reverse Linked List II	Solution	Medium
25. Reverse Nodes in k-Group	Solution	Hard
19. Remove Nth Node From End of List	Solution	Medium
82. Remove Duplicates from Sorted List II	Solution	Medium
61. Rotate List	Solution	Medium
86. Partition List	Solution	Medium
146. LRU Cache	Solution	Medium

Binary Tree General
104. Maximum Depth of Binary Tree	Solution	Easy
100. Same Tree	Solution	Easy
226. Invert Binary Tree	Solution	Easy
101. Symmetric Tree	Solution	Easy
105. Construct Binary Tree from Preorder and Inorder Traversal	Solution	Medium
106. Construct Binary Tree from Inorder and Postorder Traversal	Solution	Medium
117. Populating Next Right Pointers in Each Node II	Solution	Medium
114. Flatten Binary Tree to Linked List	Solution	Medium
112. Path Sum	Solution	Easy
129. Sum Root to Leaf Numbers	Solution	Medium
124. Binary Tree Maximum Path Sum	Solution	Hard
173. Binary Search Tree Iterator	Solution	Medium
222. Count Complete Tree Nodes	Solution	Easy
236. Lowest Common Ancestor of a Binary Tree	Solution	Medium

Binary Tree BFS
199. Binary Tree Right Side View	Solution	Medium
637. Average of Levels in Binary Tree	Solution	Easy
102. Binary Tree Level Order Traversal	Solution	Medium
103. Binary Tree Zigzag Level Order Traversal	Solution	Medium

Binary Search Tree
530. Minimum Absolute Difference in BST	Solution	Easy
230. Kth Smallest Element in a BST	Solution	Medium
98. Validate Binary Search Tree	Solution	Medium

Graph General
200. Number of Islands	Solution	Medium
130. Surrounded Regions	Solution	Medium
133. Clone Graph	Solution	Medium
399. Evaluate Division	Solution	Medium
207. Course Schedule	Solution	Medium
210. Course Schedule II	Solution	Medium

Graph BFS
909. Snakes and Ladders	Solution	Medium
433. Minimum Genetic Mutation	Solution	Medium
127. Word Ladder	Solution	Hard

Trie
208. Implement Trie (Prefix Tree)	Solution	Medium
211. Design Add and Search Words Data Structure	Solution	Medium
212. Word Search II	Solution	Hard

Backtracking
17. Letter Combinations of a Phone Number	Solution	Medium
77. Combinations	Solution	Medium
46. Permutations	Solution	Medium
39. Combination Sum	Solution	Medium
52. N-Queens II	Solution	Hard
22. Generate Parentheses	Solution	Medium
79. Word Search	Solution	Medium

Divide & Conquer
108. Convert Sorted Array to Binary Search Tree	Solution	Easy
148. Sort List	Solution	Medium
427. Construct Quad Tree	Solution	Medium
23. Merge k Sorted Lists	Solution	Hard

Kadane's Algorithm
53. Maximum Subarray	Solution	Medium
918. Maximum Sum Circular Subarray	Solution	Medium

Binary Search
35. Search Insert Position	Solution	Easy
74. Search a 2D Matrix	Solution	Medium
162. Find Peak Element	Solution	Medium
33. Search in Rotated Sorted Array	Solution	Medium
34. Find First and Last Position of Element in Sorted Array	Solution	Medium
153. Find Minimum in Rotated Sorted Array	Solution	Medium
4. Median of Two Sorted Arrays	Solution	Hard

Heap
215. Kth Largest Element in an Array	Solution	Medium
502. IPO	Solution	Hard
373. Find K Pairs with Smallest Sums	Solution	Medium
295. Find Median from Data Stream	Solution	Hard

Bit Manipulation
67. Add Binary	Solution	Easy
190. Reverse Bits	Solution	Easy
191. Number of 1 Bits	Solution	Easy
136. Single Number	Solution	Easy
137. Single Number II	Solution	Medium
201. Bitwise AND of Numbers Range	Solution	Medium

Math
9. Palindrome Number	Solution	Easy
66. Plus One	Solution	Easy
172. Factorial Trailing Zeroes	Solution	Medium
69. Sqrt(x)	Solution	Easy
50. Pow(x, n)	Solution	Medium
149. Max Points on a Line	Solution	Hard

1D DP
70. Climbing Stairs	Solution	Easy
198. House Robber	Solution	Medium
139. Word Break	Solution	Medium
322. Coin Change	Solution	Medium
300. Longest Increasing Subsequence	Solution	Medium

Multidimensional DP
120. Triangle	Solution	Medium
64. Minimum Path Sum	Solution	Medium
63. Unique Paths II	Solution	Medium
5. Longest Palindromic Substring	Solution	Medium
97. Interleaving String	Solution	Medium
72. Edit Distance	Solution	Medium
123. Best Time to Buy and Sell Stock III	Solution	Hard
188. Best Time to Buy and Sell Stock IV	Solution	Hard
221. Maximal Square	Solution	Medium

Impactful - Top 100 Liked

100 Best Rated Problems

• 100 most liked problems by LeetCoders
• Organized based on hot topics that help improve coding skills in interviews

Problems

Backtracking
17. Letter Combinations of a Phone Number	Solution	Medium
22. Generate Parentheses	Solution	Medium
39. Combination Sum	Solution	Medium
46. Permutations	Solution	Medium
51. N-Queens	Solution	Hard
78. Subsets	Solution	Medium
79. Word Search	Solution	Medium
131. Palindrome Partitioning	Solution	Medium

Binary Search
4. Median of Two Sorted Arrays	Solution	Hard
33. Search in Rotated Sorted Array	Solution	Medium
34. Find First and Last Position of Element in Sorted Array	Solution	Medium
35. Search Insert Position	Solution	Easy
74. Search a 2D Matrix	Solution	Medium
124. Binary Tree Maximum Path Sum	Solution	Hard
153. Find Minimum in Rotated Sorted Array	Solution	Medium

Binary Tree
94. Binary Tree Inorder Traversal	Solution	Easy
98. Validate Binary Search Tree	Solution	Medium
101. Symmetric Tree	Solution	Easy
102. Binary Tree Level Order Traversal	Solution	Medium
104. Maximum Depth of Binary Tree	Solution	Easy
105. Construct Binary Tree from Preorder and Inorder Traversal	Solution	Medium
108. Convert Sorted Array to Binary Search Tree	Solution	Easy
114. Flatten Binary Tree to Linked List	Solution	Medium
199. Binary Tree Right Side View	Solution	Medium
226. Invert Binary Tree	Solution	Easy
230. Kth Smallest Element in a BST	Solution	Medium
236. Lowest Common Ancestor of a Binary Tree	Solution	Medium
437. Path Sum III	Solution	Medium
543. Diameter of Binary Tree	Solution	Easy

Dynamic Programming
5. Longest Palindromic Substring	Solution	Medium
32. Longest Valid Parentheses	Solution	Hard
62. Unique Paths	Solution	Medium
64. Minimum Path Sum	Solution	Medium
70. Climbing Stairs	Solution	Easy
72. Edit Distance	Solution	Medium
118. Pascal's Triangle	Solution	Easy
139. Word Break	Solution	Medium
152. Maximum Product Subarray	Solution	Medium
198. House Robber	Solution	Medium
279. Perfect Squares	Solution	Medium
300. Longest Increasing Subsequence	Solution	Medium
322. Coin Change	Solution	Medium
416. Partition Equal Subset Sum	Solution	Medium
1143. Longest Common Subsequence	Solution	Medium

Graph
200. Number of Islands	Solution	Medium
207. Course Schedule	Solution	Medium
994. Rotting Oranges	Solution	Medium

Greedy
45. Jump Game II	Solution	Medium
55. Jump Game	Solution	Medium
121. Best Time to Buy and Sell Stock	Solution	Easy
763. Partition Labels	Solution	Medium

Hashing
1. Two Sum	Solution	Easy
49. Group Anagrams	Solution	Medium
128. Longest Consecutive Sequence	Solution	Medium
560. Subarray Sum Equals K	Solution	Medium

Heap
215. Kth Largest Element in an Array	Solution	Medium
295. Find Median from Data Stream	Solution	Hard
347. Top K Frequent Elements	Solution	Medium

Linked Lists
2. Add Two Numbers	Solution	Medium
19. Remove Nth Node From End of List	Solution	Medium
21. Merge Two Sorted Lists	Solution	Easy
23. Merge k Sorted Lists	Solution	Hard
24. Swap Nodes in Pairs	Solution	Medium
25. Reverse Nodes in k-Group	Solution	Hard
138. Copy List with Random Pointer	Solution	Medium
141. Linked List Cycle	Solution	Easy
142. Linked List Cycle II	Solution	Medium
146. LRU Cache	Solution	Medium
148. Sort List	Solution	Medium
160. Intersection of Two Linked Lists	Solution	Easy
206. Reverse Linked List	Solution	Easy
234. Palindrome Linked List	Solution	Easy

Matrix
48. Rotate Image	Solution	Medium
54. Spiral Matrix	Solution	Medium
73. Set Matrix Zeroes	Solution	Medium
240. Search a 2D Matrix II	Solution	Medium

Sliding Window
3. Longest Substring Without Repeating Characters	Solution	Medium
76. Minimum Window Substring	Solution	Hard
239. Sliding Window Maximum	Solution	Hard
438. Find All Anagrams in a String	Solution	Medium

Stack
20. Valid Parentheses	Solution	Easy
84. Largest Rectangle in Histogram	Solution	Hard
155. Min Stack	Solution	Medium
394. Decode String	Solution	Medium
739. Daily Temperatures	Solution	Medium

Two Pointers
11. Container With Most Water	Solution	Medium
15. 3Sum	Solution	Medium
42. Trapping Rain Water	Solution	Hard
283. Move Zeroes	Solution	Easy

Trie
208. Implement Trie (Prefix Tree)	Solution	Medium

Misc
31. Next Permutation	Solution	Medium
41. First Missing Positive	Solution	Hard
53. Maximum Subarray	Solution	Medium
56. Merge Intervals	Solution	Medium
75. Sort Colors	Solution	Medium
136. Single Number	Solution	Easy
169. Majority Element	Solution	Easy
189. Rotate Array	Solution	Medium
238. Product of Array Except Self	Solution	Medium
287. Find the Duplicate Number	Solution	Medium