USCode ✌️

Overview

Welcome to USCode - a collaborative coding interview preparation repository designed to help our team master technical interviews for US tech companies. This repository serves as our central hub for sharing solutions, discussing problem-solving strategies, and tracking our progress through various coding challenges.

Our mission is to build a strong foundation in data structures, algorithms, and system design while fostering a supportive learning environment where we can grow together and achieve our career goals in the US tech industry.

🧑‍💻 Members

Name
Moonsoo Park	@m0onsoo
Ji Min Lee	@masibasi
Yoonjae Hwang	@YoonjaeH
Ellie Eunsung Roh	@happysungb
Minho Jang	@wkdalsgh192

💻 Workflow & Rules

• Use the format: problem number_person name.py

• Push your solutions before the study session day and merge during the study session time

• Explain your solution process through comments (in English)

• Include LeetCode's suggested time complexity and space complexity as comments at the top of each file

🗓️ Roadmap

1️⃣ Phase 1: Foundation Building (Weeks 1-4)

Week 1: Arrays & Hashing

1. [NeetCode] #49. Group Anagrams
2. [NeetCode] #347. Top K Frequent Elements
3. [FAANG Interview] #238. Product of Array Except Self (Amazon/Meta)

Week 2: Two Pointers

1. [NeetCode] #167. Two Sum II - Input Array Is Sorted
2. [NeetCode] #15. 3Sum
3. [FAANG Interview] #11. Container With Most Water (Google/Meta)

Week 3: Sliding Window

1. [NeetCode] #3. Longest Substring Without Repeating Characters
2. [NeetCode] #424. Longest Repeating Character Replacement
3. [FAANG Interview] #567. Permutation in String (Meta)

Week 4: Stack & Binary Search

1. [NeetCode] #150. Evaluate Reverse Polish Notation
2. [NeetCode] #74. Search a 2D Matrix
3. [FAANG Interview] #33. Search in Rotated Sorted Array (Amazon/Google)

2️⃣ Phase 2: Core Pattern Mastery (Weeks 5-8)

Week 5: 1-D Dynamic Programming

1. [NeetCode] #322. Coin Change
2. [NeetCode] #139. Word Break
3. [FAANG Interview] #198. House Robber (Moloco)

Week 6: 2-D Dynamic Programming

1. [NeetCode] #62. Unique Paths
2. [NeetCode] #1143. Longest Common Subsequence
3. [FAANG Interview] #140. Word Break II (Amazon/Google)

Week 7: Linked List

1. [NeetCode] #19. Remove Nth Node From End of List
2. [NeetCode] #143. Reorder List
3. [FAANG Interview] #2. Add Two Numbers (Amazon/Meta)

Week 8: Trees

1. [NeetCode] #102. Binary Tree Level Order Traversal
2. [NeetCode] #98. Validate Binary Search Tree
3. [FAANG Interview] #230. Kth Smallest Element in a BST (Amazon/Meta)

3️⃣ Phase 3: Advanced & Real-world Preparation (Weeks 9-11)

Week 9: Heaps (Priority Queue) & Tries

1. [NeetCode] #973. K Closest Points to Origin
2. [NeetCode] #211. Design Add and Search Words Data Structure
3. [FAANG Interview] #215. Kth Largest Element in an Array (Amazon/Meta)

Week 10: Backtracking & Graphs

1. [NeetCode] #46. Permutations
2. [NeetCode] #207. Course Schedule
3. [FAANG Interview] #79. Word Search (Amazon/Meta)

Week 11: Greedy & Intervals

1. [NeetCode] #55. Jump Game
2. [NeetCode] #56. Merge Intervals
3. [FAANG Interview] #435. Non-overlapping Intervals (Meta/Google)

Week 12: Bit Manipulation

1. [NeetCode] #7. Reverse Integer
2. [NeetCode] #371. Sum of Two Integers
3. [FAANG Interview] #137. Single Number II (Google/Amazon/Apple)

4️⃣ Phase 4: Randomized Mock Interviews (Weeks 13-20)

Week 13

1. [Easy] #680. Valid Palindrome II
2. [Easy] #226. Invert Binary Tree
3. [Medium] #695. Max Area of Island
4. [Medium] #287. Find the Duplicate Number
5. [Hard] #135. Candy

Week 14

1. [Easy] #122. Best Time to Buy and Sell Stock II
2. [Easy] #71. Simplify Path
3. [Medium] #133. Clone Graph
4. [Medium] #213. House Robber II
5. [Hard] #23. Merge k Sorted Lists

Week 15

1. [Easy] #104. Maximum Depth of Binary Tree
2. [Easy] #217. Contains Duplicate
3. [Medium] #54. Spiral Matrix
4. [Medium] #518. Coin Change II
5. [Hard] #76. Minimum Window Substring

Week 16

1. [Easy] #242. Valid Anagram
2. [Easy] #141. Linked List Cycle
3. [Medium] #210. Course Schedule II
4. [Medium] #53. Maximum Subarray
5. [Hard] #297. Serialize and Deserialize Binary Tree

Week 17

1. [Easy] #70. Climbing Stairs
2. [Easy] #543. Diameter of Binary Tree
3. [Medium] #994. Rotting Oranges
4. [Medium] #560. Subarray Sum Equals K
5. [Hard] #127. Word Ladder

Week 18

1. [Easy] #206. Reverse Linked List
2. [Easy] #704. Binary Search
3. [Medium] #17. Letter Combinations of a Phone Number
4. [Medium] #739. Daily Temperatures
5. [Hard] #295. Find Median from Data Stream

Week 19

1. [Easy] #110. Balanced Binary Tree
2. [Easy] #1. Two Sum
3. [Medium] #130. Surrounded Regions
4. [Medium] #152. Maximum Product Subarray
5. [Hard] #84. Largest Rectangle in Histogram

Week 20

1. [Easy] #572. Subtree of Another Tree
2. [Easy] #155. Min Stack
3. [Medium] #684. Redundant Connection
4. [Medium] #438. Find All Anagrams in a String
5. [Hard] #124. Binary Tree Maximum Path Sum

5️⃣ Phase 5: High-Frequency Mix (Weeks 21-28)

Week 21

1. [Easy] #268. Missing Number
2. [Easy] #100. Same Tree
3. [Medium] #417. Pacific Atlantic Water Flow
4. [Medium] #36. Valid Sudoku
5. [Hard] #239. Sliding Window Maximum

Week 22

1. [Easy] #21. Merge Two Sorted Lists
2. [Easy] #1046. Last Stone Weight
3. [Medium] #399. Evaluate Division
4. [Medium] #5. Longest Palindromic Substring
5. [Hard] #25. Reverse Nodes in k-Group

Week 23

1. [Easy] #234. Palindrome Linked List
2. [Easy] #338. Counting Bits
3. [Medium] #73. Set Matrix Zeroes
4. [Medium] #621. Task Scheduler
5. [Hard] #329. Longest Increasing Path in a Matrix

Week 24

1. [Easy] #108. Convert Sorted Array to BST
2. [Easy] #392. Is Subsequence
3. [Medium] #743. Network Delay Time
4. [Medium] #146. LRU Cache
5. [Hard] #41. First Missing Positive

Week 25

1. [Easy] #617. Merge Two Binary Trees
2. [Easy] #283. Move Zeroes
3. [Medium] #48. Rotate Image
4. [Medium] #91. Decode Ways
5. [Hard] #212. Word Search II

Week 26

1. [Easy] #160. Intersection of Two Linked Lists
2. [Easy] #509. Fibonacci Number
3. [Medium] #138. Copy List with Random Pointer
4. [Medium] #300. Longest Increasing Subsequence
5. [Hard] #4. Median of Two Sorted Arrays

Week 27

1. [Easy] #112. Path Sum
2. [Easy] #202. Happy Number
3. [Medium] #542. 01 Matrix
4. [Medium] #16. 3Sum Closest
5. [Hard] #10. Regular Expression Matching

Week 28

1. [Easy] #190. Reverse Bits
2. [Easy] #94. Binary Tree Inorder Traversal
3. [Medium] #547. Number of Provinces
4. [Medium] #452. Minimum Number of Arrows to Burst Balloons
5. [Hard] #85. Maximal Rectangle

📚 References

Primary Resources

• LeetCode - The gold standard for coding interview practice
• NeetCode - Structured learning path with video explanations

Additional Study Materials

• This is Coding Test - Algorithm-specific YouTube video guide in Korean
• Cracking the Coding Interview - Classic book by Gayle Laakmann McDowell
• Algorithms, Part I & II (Princeton) - Free Coursera course by Robert Sedgewick
• System Design Interview - Alex Xu's comprehensive system design guide
• Blind 75 - Curated list of the most important LeetCode problems
• Grokking the Coding Interview - Pattern-based approach to coding interviews

Practice Platforms

• HackerRank - Additional practice problems
• CodeSignal - Company-specific practice tests
• Pramp - Mock interview practice with peers

Interview Preparation

• InterviewBit - Structured learning paths
• GeeksforGeeks - Comprehensive algorithm explanations
• YouTube - Back To Back SWE - High-quality coding interview explanations