LeetCode Hero

From Zero to Leetcode Hero

Welcome to LeetCode Hero, a repository that documents my journey of mastering algorithms and data structures. This project serves as both a personal learning journal and a professional portfolio of my solutions, implemented in Modern C++ and Haskell.

• ⭐ Star this repository if you find it helpful!
• 🔄 Share with others learning functional programming
• 🤝 Contributions welcome - especially Haskell optimizations!

My Approach

• Modern C++: Solutions in C++ are written to reflect clean, efficient, and production-ready code, mirroring my professional work as a compiler engineer.
• Haskell: Solutions in Haskell are an exploration of functional programming paradigms, used to tackle problems from a different perspective and for mental training.

Repository Structure

Each problem is contained in its own directory, named with its LeetCode number and title for easy navigation (e.g., 001_Two_Sum). Explanations are added for some solutions as I refine my understanding.

About Me

Feel free to check out my other projects on my GitHub Profile.

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Progress Tracker

Phase 1: The Diagnostic (The Awareness Pass)

• Build and complete the CultivationDB.yaml database.

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Phase 2: The Triage (The "Debt List") - [PRIORITY: ACTIVE]

This is the task we discussed on Sept 6-7. Phase 1 (Diagnosis) revealed a clear "Debt List" of forgotten critical topics. This is your immediate homework.

• Mission: Attack the L1_FORGOT List. Treat these 10 problems as "new" and re-learn them from scratch.

• Goal: Convert all 10 of these from L1 to at least L2_STRUGGLE by mid-September.

• The Debt List (The 7 "L1_FORGOT" entries from YAML):

  • 211 (Design Add/Search Trie) - (Trie Data Structure)
  • 207 (Course Schedule I) - (Kahn's / Topological Sort)
  • 210 (Course Schedule II) - (Graph Cycle Check)
  • 152 (Max Product Subarray)
  • 155 (Min Stack)
  • 239 (Sliding Window Max) - (Monotonic Queue)
  • 416 (Partition Equal Subset Sum) - (Knapsack DP)
  • 230 (Kth Smallest Element in a BST)
  • 206 (Reverse Linked List)

• The 2 Missing Problems (The "New Debt"):

  • 004 (Median of Two Sorted Arrays) - (Hard Binary Search)
  • 556 (Next Greater Element III)
  • 918 Maximum Sum Circular Subarray (kadane's algorithm variant)

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Phase 3: The Integration - Mindful Mastery

Mission: To systematically clear foundational weaknesses and the L2_STRUGGLE list by merging deliberate practice with the mindfulness techniques defined in the "LeetCode 心法練習 SOP". The goal is not just to solve problems, but to achieve a state of calm, focused flow while doing so.

Topic Mastery Checklist:

• Theme: Linked List
  • Complete all Neetcode 150 Linked List problems (2/13)
  • Review all L2_STRUGGLE Linked List problems from CultivationDB.yaml
• Theme: Trees (Basics & Traversal) (6/6)
• Theme: Trees (Advanced) (9/9)
• Theme: DP / Graphs / etc.
  • Systematically work through other L2_STRUGGLE topics from CultivationDB.yaml
• Theme: System Design (Introduction)
  • Watch/Read 2-3 introductory pieces of content on System Design per week (e.g., foundational concepts, classic problem overviews). (0/10)

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Phase 4: The Synthesis - Holistic Interview Prep

Prerequisite: This phase begins when the L2_STRUGGLE list feels manageable and you have built confidence in the core topics from Phase 3. The focus shifts from topic-by-topic learning to integrated, mock-interview-style practice.

Mission: To synthesize all required skills—algorithmic fluency, system design, and behavioral communication—into a cohesive, interview-ready whole.

The Three Pillars of Preparation:

• Pillar 1: Algorithmic Fluency

  • Conduct full-length (45 min) mock coding interviews (0/5)
  • Review all L3_MASTERED problems to ensure instant recall (0/20)
  • Tackle a curated list of Hard problems to expand boundaries (0/5)

• Pillar 2: System Design

  • Study and summarize foundational System Design concepts (e.g., CAP Theorem, Caching, Load Balancing, Databases) (0/5)
  • Practice explaining the architecture of classic problems aloud (e.g., Design Twitter, Design a URL Shortener, Design a Web Crawler) (0/5)
  • Conduct full-length (45 min) mock System Design interviews (0/3)

• Pillar 3: Behavioral & Communication

  • Draft and refine 5-7 key project stories using the STAR method.
  • Practice telling your stories aloud, focusing on clarity and impact.
  • Prepare thoughtful questions to ask your interviewers.
  • Review your "About Me" and professional narrative from your resume.