LeetCode C++ Solutions Repository

A collection of LeetCode algorithm problem solutions implemented in modern C++. This repository serves as a learning platform to help me become a master of C++ and DSA through systematic problem-solving.

🎯 Purpose

This repository is designed for:

• Learning and mastering DSA concepts through practical problem-solving
• Improving C++ programming skills using modern features when beneficial
• Building comprehensive knowledge of algorithms and data structures
• Systematic learning to become a C++ and DSA master

🚀 Modern C++ Features

This repository uses modern C++ features to write clean, efficient, and maintainable solutions:

• Modern algorithms - Range-based algorithms and efficient data processing
• Smart containers - Appropriate data structures for each problem
• Error handling - Robust and safe code practices
• Advanced concepts - Templates, concepts, and compile-time features
• Performance optimization - Move semantics, perfect forwarding, and efficient code

📚 Problems Solved

🎯 Array & Hashing

Key Patterns:

• Hash Map/Set: Two Sum, Contains Duplicate, Valid Anagram, Group Anagrams
• Array Manipulation: Product of Array Except Self, Longest Consecutive Sequence
• String Processing: Valid Anagram, Group Anagrams, Encode and Decode Strings
• Matrix/2D Arrays: Valid Sudoku
• Frequency Counting: Top K Frequent Elements, Valid Anagram, Group Anagrams

Problems:

• 1. Two Sum - Easy
• 36. Valid Sudoku - Medium
• 49. Group Anagrams - Medium
• 128. Longest Consecutive Sequence - Medium
• 217. Contains Duplicate - Easy
• 238. Product of Array Except Self - Medium
• 242. Valid Anagram - Easy 41→- 271. Encode and Decode Strings - Medium 42→- 347. Top K Frequent Elements - Medium 43→ 44→### 🎯 Binary Search 45→Key Patterns: 46→- Classic Binary Search: Search in sorted arrays 47→- Binary Search on Answer: Optimize over monotonic predicates (Koko Eating Bananas) 48→- Binary Search on Rotated/Transformed Data: Rotated arrays, 2D matrices 49→- Binary Search in Time/Value Space: Time-based key-value store, median of two arrays 50→ 51→Problems: 52→- 4. Median of Two Sorted Arrays - Hard 53→- 33. Search in Rotated Sorted Array - Medium 54→- 74. Search a 2D Matrix - Medium 55→- 153. Find Minimum in Rotated Sorted Array - Medium 56→- 704. Binary Search - Easy 57→- 875. Koko Eating Bananas - Medium 58→- 981. Time Based Key-Value Store - Medium 59→ 44→### 🎯 Two Pointers Key Patterns:
• Opposite Direction: Valid Palindrome, Container With Most Water
• Same Direction: Two Sum II - Input Array Is Sorted, 3Sum
• Prefix/Suffix Arrays: Trapping Rain Water
• Greedy + Two Pointers: Container With Most Water
• Sorting + Two Pointers: 3Sum

Problems:

• 11. Container With Most Water - Medium
• 15. 3Sum - Medium
• 42. Trapping Rain Water - Hard
• 125. Valid Palindrome - Easy
• 167. Two Sum II - Input Array Is Sorted - Easy

🎯 Sliding Window

Key Patterns:

• Fixed Size Window: Analyze subarrays of fixed length k
• Variable Size Window: Expand/shrink window based on constraints
• Hash Map + Sliding Window: Track frequency/indices within window

Problems:

• 3. Longest Substring Without Repeating Characters - Medium
• 121. Best Time to Buy and Sell Stock - Easy

🎯 Stack

Key Patterns:

• LIFO Operations: Valid Parentheses, Min Stack, Evaluate Reverse Polish Notation
• Monotonic Stack: Daily Temperatures, Largest Rectangle in Histogram
• Expression Evaluation: Evaluate Reverse Polish Notation
• Nested Structure Processing: Valid Parentheses, Generate Parentheses
• Auxiliary Stack: Min Stack (tracking minimum), Car Fleet (tracking time)

Problems:

• 20. Valid Parentheses - Easy
• 22. Generate Parentheses - Medium
• 84. Largest Rectangle in Histogram - Hard
• 150. Evaluate Reverse Polish Notation - Medium
• 155. Min Stack - Medium
• 739. Daily Temperatures - Medium
• 853. Car Fleet - Medium

🛠️ Development Setup

Simple Compilation

For basic testing, you can compile individual solutions:

# Navigate to problem directorycd"src/1. Two Sum"# Compile with C++23
g++ -std=c++23 -O2 main.cpp -o solution
# or
clang++ -std=c++23 -O2 main.cpp -o solution
# Run
./solution

Compiler Requirements

• GCC: Version 13+ with -std=c++23
• Clang: Version 17+ with -std=c++23
• MSVC: Version 19.35+ with /std:c++23

📝 Contributing

1. Fork the repository
2. Create a new branch for your solution
3. Add your solution in the appropriate problem directory
4. Follow the existing naming convention: Problem Number. Problem Name/
5. Submit a pull request

Solution Guidelines

• Use C++23 standard - Leverage modern features when beneficial
• Write clear, readable code with proper comments
• Include problem description in comments
• Follow C++23 best practices - RAII, smart pointers, constexpr
• Test solutions with multiple test cases
• Include time and space complexity analysis
• Document C++23 features used in your solution

🧠 Learning Approach

Comprehensive Documentation System

• Problem-Specific Learning: Each problem includes detailed README with multiple approaches
• C++ Mastery: Extensive C++ documentation covering fundamentals to advanced topics
• DSA Foundation: Complete data structures and algorithms reference
• Pattern Recognition: Common algorithmic patterns and when to use them
• Progressive Learning: Structured roadmap from basics to advanced concepts

Knowledge Building Strategy

• Theory + Practice: Combine conceptual understanding with hands-on coding
• Multiple Solutions: Learn different approaches to the same problem
• Modern C++: Use latest C++23 features for efficient and clean code
• Systematic Progress: Track learning through comprehensive documentation
• Mastery Focus: Deep understanding over quick solutions

📊 Progress Tracking

Quick Stats

• Total Problems: 30
• Categories: Array & Hashing, Binary Search, Two Pointers, Sliding Window, Stack
• Easy: 8 | Medium: 19 | Hard: 3

C++23 Features Used

• STL Containers: std::unordered_map, std::unordered_set, std::priority_queue, std::vector, std::string, std::stack
• STL Algorithms: std::sort, std::transform, std::accumulate, std::ranges, std::is_sorted, std::max_element
• Modern C++: std::ranges, std::views, std::format, auto keyword, structured bindings, constexpr, std::tuple
• Two Pointers: Efficient array traversal, sliding window techniques, greedy algorithms
• Stack Operations: LIFO data structure, monotonic stack patterns, expression evaluation, nested structure processing

📖 Learning Resources

Repository Documentation

• Learning Roadmap - Comprehensive learning path for C++ and DSA mastery
• C++ Documentation - Complete C++ programming concepts and modern features
• DSA Documentation - Data structures and algorithms fundamentals to advanced topics
• Algorithm Patterns - Common algorithmic patterns and techniques
• Problem Categories - Problems organized by topic and difficulty

External Resources

• LeetCode Official Website
• Neetcode 150 Roadmap
• C++23 Reference
• C++23 Standard
• std::ranges Documentation
• std::views Documentation
• Algorithm Visualization
• C++ Core Guidelines
• Modern C++ Features

📄 License

This project is open source and available under the MIT License.

🤝 Acknowledgments

• ISO C++ Committee for C++23 standard
• LeetCode for providing excellent algorithmic problems
• The C++ community for continuous improvements to the language
• All contributors who help improve this repository

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Happy Learning! 🚀✨

This repository is designed for comprehensive learning and mastery building, focusing on DSA concepts and modern C++ programming.