LeetCode Solutions – by Hwangfucius

About

This page collects my personal solutions for various problems from LeetCode. Each page includes the code, reasoning, and alternative ideas when relevant.

Problem List

Problem 1 – Two Sum
Problem 2 – Add Two Numbers
Problem 3 – Longest Substring Without Repeating Characters
Problem 4 – Median of Two Sorted Arrays
Problem 5 – Longest Palindromic Substring
Problem 6 – Zigzag Conversion
Problem 7 - Reverse Integer
Problem 8 - String to Integer (atoi)
Problem 9 - Palindrome Number
Problem 10 - Regular Expression Matching
Problem 11 - Container with Most Water
Problem 12 - Integer to Roman
Problem 13 - Roman to Integer
Problem 14 - Longest Common Prefix
Problem 15 - 3Sum
Problem 16 - 3Sum Closest
Problem 17 - Letter Combinations of a Phone Number
Problem 18 - 4Sum
Problem 19 - Remove N-th Node from End of List
Problem 20 - Valid Parentheses
Problem 21 - Merge Two Sorted Lists
Problem 22 - Generate Parentheses
Problem 23 - Merge k Sorted Lists
Problem 24 - Swap Nodes in Pairs
Problem 25 - Reverse Nodes in k-Group
Problem 26 - Remove Duplicates from Sorted Array
Problem 27 - Remove Element
Problem 28 - Find the Index of the First Occurrence in a String
Problem 29 - Divide Two Integers
Problem 31 - Next Permutation
Problem 32 - Longest Valid Parentheses
Problem 33 - Search in Rotated Sorted Array
Problem 34 - Find First and Last Position of Element in Sorted Array
Problem 35 - Search Insert Position
Problem 36 - Valid Sudoku
Problem 38 - Count and Say
Problem 39 - Combination Sum
Problem 46 - Permutations
Problem 53 - Maximum Subarray
Problem 54 - Spiral Matrix
Problem 58 - Length of Last Word
Problem 62 - Unique Paths
Problem 63 - Unique Paths II
Problem 64 - Minimum Path Sum
Problem 66 - Plus One
Problem 67 - Add Binary
Problem 70 - Climbing Stairs
Problem 72 - Edit Distance
Problem 76 - Minimum Window Substring
Problem 89 - Gray Code
Problem 94 - Binary Tree Inorder Traversal
Problem 104 - Maximum Depth of Binary Tree
Problem 112 - Path Sum
Problem 113 - Path Sum II
Problem 118 - Pascal's Triangle
Problem 119 - Pascal's Triangle II
Problem 128 - Longest Consecutive Sequence
Problem 137 - Single Number II
Problem 141 - Linked List Cycle
Problem 150 - Evaluate Reverse Polish Notation
Problem 167 - Two Sum II - Input Array Is Sorted
Problem 206 - Reverse Linked List
Problem 217 - Contains Duplicate
Problem 238 - Product of Array Except Self
Problem 242 - Valid Anagram
Problem 283 - Move Zeroes
Problem 338 - Couting Bits
Problem 347 - Top K Frequent Elements
Problem 392 - Is Subsequence
Problem 509 - Fibonacci Number

How This Project Is Organized

The layout is intentionally minimal and mirrors my Project Euler setup:

Each problem is stored as its own HTML file under docs/.
Code snippets are written in TypeScript unless otherwise specified.
When needed, I may link to full source files in my GitHub repo.

Repository

All solution files are versioned in my GitHub repository.