LeetCode 2025 - Problem Solutions & Documentation

A comprehensive collection of LeetCode problem solutions with detailed documentation, pattern recognition, and optimization analysis.

📚 Problem Index

Easy Problems

#	Problem	Solution	Documentation	Pattern
1071	Greatest Common Divisor of Strings	Python	📖	String Manipulation
1768	Merge Strings Alternately	Python	📖	Two Pointers

Medium Problems

#	Problem	Solution	Documentation	Pattern
151	Reverse Words in a String	Python	📖	String Processing
238	Product of Array Except Self	Python	📖	Left-Right Product Accumulation

Hard Problems

#	Problem	Solution	Documentation	Pattern
-	Coming Soon...	-	-	-

🎯 Pattern Categories

Array Processing

• 238. Product of Array Except Self - Left-Right Product Accumulation

String Manipulation

• 1071. Greatest Common Divisor of Strings - String Pattern Recognition
• 1768. Merge Strings Alternately - Two Pointers / Alternating Pattern
• 151. Reverse Words in a String - String Processing

Two Pointers

• 1768. Merge Strings Alternately - Alternating merge pattern

📊 Statistics

• Total Problems: 4
• Easy: 2
• Medium: 2
• Hard: 0
• Documentation Coverage: 100%

🚀 Quick Start

1. Browse by Difficulty: Navigate to easy/, medium/, or hard/ folders
2. Read Documentation: Each problem has comprehensive .md documentation
3. Study Patterns: Focus on the pattern recognition sections
4. Test Solutions: Run the Python implementations
5. Follow Template: Use DOCUMENTATION_TEMPLATE.md for new problems

📖 Documentation Features

Each problem documentation includes:

• ✅ Core Requirements - Essential problem constraints and success criteria
• ✅ Pattern Recognition - Algorithmic pattern identification
• ✅ Visual Walkthrough - Step-by-step solution explanation
• ✅ Implementation - Clean, optimized code with comments
• ✅ Complexity Analysis - Time/space complexity breakdown
• ✅ Edge Cases - Challenging scenarios and handling
• ✅ Alternative Approaches - Other methods and trade-offs
• ✅ Common Mistakes - Pitfalls to avoid
• ✅ Related Problems - Similar pattern problems
• ✅ Test Cases - Comprehensive test suite

🎯 Study Strategy

Based on LEETCODE_STRATEGY.md:

Phase 1: Pattern Recognition (Current)

• Study existing documented problems
• Identify common patterns and techniques
• Build pattern recognition skills

Phase 2: Pattern Application

• Apply learned patterns to new problems
• Focus on implementation speed
• Optimize for time/space complexity

Phase 3: Advanced Techniques

• Tackle hard problems
• Learn advanced algorithms
• Master complex data structures

📝 Contributing

When adding new problems:

1. Follow Template: Use DOCUMENTATION_TEMPLATE.md
2. Update Index: Add entry to this README.md file
3. Pattern Classification: Identify and document the algorithmic pattern
4. Test Coverage: Include comprehensive test cases
5. Quality Check: Verify all 17 template sections are complete

🔗 Quick Links

• 📋 Documentation Template
• 🎯 Study Strategy
• 📁 Easy Problems
• 📁 Medium Problems
• 📁 Hard Problems

🏆 Goals

• Short-term: Document 50+ problems with comprehensive analysis
• Medium-term: Master 15+ algorithmic patterns
• Long-term: Achieve consistent problem-solving efficiency across all difficulty levels

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Last Updated: July 13, 2025
Problems Documented: 4
Documentation Coverage: 100%