A comprehensive collection of Data Structures and Algorithms solutions following the NeetCode roadmap. Perfect for interview preparation, learning, and mastering problem-solving patterns.
- Overview
- Repository Structure
- Problem Categories
- Getting Started
- How to Use This Repository
- Code Structure
- Learning Path
- Contributing
- Resources
- FAQ
- License
This repository contains 150+ LeetCode problems organized by topic and difficulty level, following the popular NeetCode roadmap. Each solution includes:
- ✅ Clean, readable Python code with descriptive variable names
- 📝 Detailed problem descriptions from LeetCode
- 🧠 Multiple solution approaches (when applicable)
- ⏱️ Time and Space complexity analysis for each approach
- 🧪 Comprehensive test cases with expected outputs
- 💡 In-line comments explaining the logic
- Beginner-Friendly: Each solution is self-contained and easy to understand
- Interview-Ready: Covers all major DSA patterns asked in FAANG interviews
- Progressive Learning: Organized from Easy → Medium → Hard difficulty
- Pattern Recognition: Learn to identify and apply common problem-solving patterns
- Production-Quality: Code follows best practices and PEP 8 style guidelines
NEETCODE ROADMAP/
│
├── ARRAYS AND HASHING/ # Easy problems (68 solutions)
├── ARRAYS AND HASHING MEDIUM/ # Medium problems (33 solutions)
│
├── TWO POINTERS/ # Easy problems (16 solutions)
├── TWO POINTERS MEDIUM/ # Medium problems (18 solutions)
│
├── SLIDING WINDOW/ # Easy problems (5 solutions)
├── SLIDING WINDOW MEDIUM/ # Medium problems (27 solutions)
├── SLIDING WINDOW HARD/ # Hard problems (2 solutions)
│
├── STACK/ # Easy problems (7 solutions)
├── STACK MEDIUM/ # Medium problems (14 solutions)
│
└── README.md # This file
All files follow a consistent naming pattern:
- Lowercase with no spaces:
twosum.py,validpalindrome.py - Descriptive names: Match the LeetCode problem title
- Easy to search: Use Ctrl+F to find problems quickly
Total: 101 problems (68 Easy + 33 Medium)
Core concepts covered:
- Hash Maps and Hash Sets
- Frequency counting
- Prefix sums
- Array manipulation
- String processing
Key Problems:
- Two Sum
- Group Anagrams
- Valid Anagram
- Contains Duplicate
- Top K Frequent Elements
Total: 34 problems (16 Easy + 18 Medium)
Core concepts covered:
- Left-right pointer technique
- Fast-slow pointer (Floyd's algorithm)
- Sliding window variations
- In-place array modifications
Key Problems:
- Valid Palindrome
- Two Sum II
- Container With Most Water
- Trapping Rain Water
Total: 34 problems (5 Easy + 27 Medium + 2 Hard)
Core concepts covered:
- Fixed-size windows
- Variable-size windows
- Optimization problems
- Substring problems
Key Problems:
- Best Time to Buy and Sell Stock
- Longest Substring Without Repeating Characters
- Minimum Window Substring
- Sliding Window Maximum
Total: 21 problems (7 Easy + 14 Medium)
Core concepts covered:
- LIFO (Last In First Out) operations
- Monotonic stacks
- Expression evaluation
- Parentheses matching
Key Problems:
- Valid Parentheses
- Min Stack
- Daily Temperatures
- Largest Rectangle in Histogram
- Python 3.7 or higher installed on your system
- Basic understanding of Python syntax
- A code editor (VS Code, PyCharm, or any text editor)
-
Clone the repository
git clone https://github.com/aridepai17/neetcode-roadmap.git cd neetcode-roadmap -
No dependencies required! All solutions use Python's standard library only. No external packages needed.
-
Verify Python installation
python --version # Should output: Python 3.7.x or higher
- Start with Easy problems in the
ARRAYS AND HASHINGfolder - Read the problem description at the top of each file
- Try solving it yourself before looking at the solution
- Study the solution and understand the approach
- Analyze the complexity to understand efficiency
- Run the test cases to verify your understanding
# Navigate to any folder
cd "ARRAYS AND HASHING"
# Run any Python file
python twosum.pyExpected Output:
[0, 1]
[1, 2]
[0, 1]
...
- Focus on patterns, not memorization
- Time yourself (aim for 20-30 minutes per problem)
- Practice explaining your solution out loud
- Review complexity analysis for each solution
- Revisit problems after a few days to reinforce learning
- Compare multiple solution approaches
- Optimize space/time complexity
- Implement solutions in other languages
- Add edge case test scenarios
- Contribute improvements via Pull Requests
Every solution file follows this consistent structure:
# PROBLEM TITLE
'''
Problem Description:
Detailed explanation of what the problem asks for,
including constraints and requirements.
'''
def solutionFunction(params):
# Implementation with clear logic
# Step-by-step approach
# Efficient algorithm
pass
'''
Time Complexity: O(n)
Detailed explanation of why this complexity...
Space Complexity: O(1)
Detailed explanation of space usage...
'''
# Test Cases
testCase1 = [...]
print(solutionFunction(testCase1)) # Output: expected_result- ✅ PEP 8 compliant: Follows Python style guidelines
- ✅ Descriptive naming: Variables and functions have clear names
- ✅ Comments: Complex logic is explained
- ✅ Type hints: (where applicable) for better code clarity
- ✅ Edge cases: Test cases cover normal and edge scenarios
Week 1-2: Arrays and Hashing (Easy)
↓
Week 3-4: Two Pointers (Easy)
↓
Week 5-6: Sliding Window (Easy → Medium)
↓
Week 7-8: Stack (Easy → Medium)
↓
Week 9-10: Arrays and Hashing (Medium)
↓
Week 11-12: Two Pointers (Medium)
↓
Week 13+: Advanced topics and Hard problems
- Consistency over intensity: Solve 2-3 problems daily
- Understand, don't memorize: Focus on the "why" behind solutions
- Write it out: Code solutions from scratch without copy-paste
- Review regularly: Revisit solved problems weekly
- Join communities: Discuss solutions with peers
| Pattern | When to Use | Example Problems |
|---|---|---|
| Hash Map | Need O(1) lookup, counting frequency | Two Sum, Group Anagrams |
| Two Pointers | Sorted array, palindrome check | Valid Palindrome, Container With Most Water |
| Sliding Window | Subarray/substring problems | Longest Substring, Max Sum Subarray |
| Stack | Matching pairs, next greater element | Valid Parentheses, Daily Temperatures |
Contributions are welcome! Here's how you can help:
- 🐛 Report bugs or issues in solutions
- 💡 Suggest optimizations or alternative approaches
- 📚 Add more test cases for edge scenarios
- 🌐 Translate solutions to other languages
- 📖 Improve documentation and explanations
- ✨ Add new problems following the existing structure
- Fork the repository
- Create a feature branch (
git checkout -b feature/improvement) - Follow the existing code structure and style
- Add test cases for new solutions
- Update README if adding new categories
- Commit with clear messages (
git commit -m "Add: Two Sum solution") - Push to your branch (
git push origin feature/improvement) - Open a Pull Request
- NeetCode.io - Video explanations for each problem
- LeetCode - Original problem statements and online judge
- Big-O Cheat Sheet - Time/space complexity reference
- Python Documentation - Official Python docs
- Cracking the Coding Interview by Gayle Laakmann McDowell
- Elements of Programming Interviews in Python by Aziz, Lee, Prakash
- Introduction to Algorithms by CLRS
- NeetCode - Problem walkthroughs
- Abdul Bari - Algorithm fundamentals
- Back To Back SWE - In-depth explanations
A: No! Basic Python knowledge (loops, conditionals, functions) is sufficient. Each solution is beginner-friendly.
A: At 2-3 problems per day, approximately 2-3 months. Focus on understanding over speed.
A: Yes, but we encourage you to understand and type them yourself rather than copy-paste.
A: Python's clean syntax makes it ideal for learning algorithms. The logic translates easily to other languages.
A: Currently, the repository focuses on Easy and Medium problems. Hard problems will be added progressively.
A: Create a checklist or use the GitHub issues feature to mark completed problems.
A: Check the NeetCode video explanation, or open an issue asking for clarification. Community help is available!
Track your journey through the roadmap:
- Arrays and Hashing - Easy (68 problems)
- Arrays and Hashing - Medium (33 problems)
- Two Pointers - Easy (16 problems)
- Two Pointers - Medium (18 problems)
- Sliding Window - Easy (5 problems)
- Sliding Window - Medium (27 problems)
- Sliding Window - Hard (2 problems)
- Stack - Easy (7 problems)
- Stack - Medium (14 problems)
Total Progress: 0 / 190 problems completed 🎯
This project is licensed under the MIT License - see the LICENSE file for details.
- NeetCode for the excellent roadmap and video explanations
- LeetCode for providing the problem platform
- The coding community for continuous learning and support
- Issues: GitHub Issues
- Discussions: GitHub Discussions
- Email: your.email@example.com
Happy Coding! 🚀
Remember: The goal is not to solve all problems, but to understand the patterns and think algorithmically.
- Nov 2024: Initial repository setup with 190+ problems
- Added comprehensive documentation
- Organized problems by difficulty and topic
- Included complexity analysis for all solutions