📝 Mastery Progress Tracker

🔵 Pillar 1: Data Structures & Algorithms (DSA Lab)

01. Arrays & Hashing

• [ ] Contains Duplicate
• [ ] Valid Anagram
• [ ] Two Sum
• [ ] Group Anagrams
• [ ] Top K Frequent Elements
• [ ] Product of Array Except Self
• [ ] Valid Sudoku
• [ ] Encode and Decode Strings
• [ ] Longest Consecutive Sequence

02. Two Pointers

• [ ] Valid Palindrome
• [ ] Two Sum II
• [ ] 3Sum
• [ ] Container With Most Water
• [ ] Trapping Rain Water

03. Sliding Window

• [ ] Best Time to Buy and Sell Stock
• [ ] Longest Substring Without Repeating Characters
• [ ] Longest Repeating Character Replacement
• [ ] Permutation in String
• [ ] Minimum Window Substring
• [ ] Sliding Window Maximum

04. Stack

• [ ] Valid Parentheses
• [ ] Min Stack
• [ ] Evaluate Reverse Polish Notation
• [ ] Generate Parentheses
• [ ] Daily Temperatures
• [ ] Car Fleet
• [ ] Largest Rectangle in Histogram

05. Binary Search

• [ ] Binary Search
• [ ] Search a 2D Matrix
• [ ] Koko Eating Bananas
• [ ] Find Minimum in Rotated Sorted Array
• [ ] Search in Rotated Sorted Array
• [ ] Time Based Key-Value Store
• [ ] Median of Two Sorted Arrays

06. Linked List

• [ ] Reverse Linked List
• [ ] Merge Two Sorted Lists
• [ ] Reorder List
• [ ] Remove Nth Node From End of List
• [ ] Copy List with Random Pointer
• [ ] Add Two Numbers
• [ ] Linked List Cycle
• [ ] Find the Duplicate Number
• [ ] LRU Cache
• [ ] Merge K Sorted Lists
• [ ] Reverse Nodes in K Group

07. Trees

• [ ] Invert Binary Tree
• [ ] Maximum Depth of Binary Tree
• [ ] Diameter of Binary Tree
• [ ] Balanced Binary Tree
• [ ] Same Tree
• [ ] Subtree of Another Tree
• [ ] Lowest Common Ancestor of BST
• [ ] Binary Tree Level Order Traversal
• [ ] Binary Tree Right Side View
• [ ] Count Good Nodes in Binary Tree
• [ ] Validate Binary Search Tree
• [ ] Kth Smallest Element in BST
• [ ] Construct Binary Tree from Preorder/Inorder
• [ ] Binary Tree Maximum Path Sum
• [ ] Serialize and Deserialize Binary Tree

08. Tries

• [ ] Implement Trie
• [ ] Design Add and Search Words
• [ ] Word Search II

09. Heap / Priority Queue

• [ ] Kth Largest Element in a Stream
• [ ] Last Stone Weight
• [ ] K Closest Points to Origin
• [ ] Kth Largest Element in an Array
• [ ] Task Scheduler
• [ ] Design Twitter
• [ ] Find Median from Data Stream

10. Backtracking

• [ ] Subsets
• [ ] Combination Sum
• [ ] Permutations
• [ ] Subsets II
• [ ] Combination Sum II
• [ ] Word Search
• [ ] Palindrome Partitioning
• [ ] Letter Combinations of a Phone Number
• [ ] N-Queens

11. Graphs

• [ ] Number of Islands
• [ ] Max Area of Island
• [ ] Clone Graph
• [ ] Walls and Gates
• [ ] Rotting Oranges
• [ ] Pacific Atlantic Water Flow
• [ ] Surrounded Regions
• [ ] Course Schedule
• [ ] Course Schedule II
• [ ] Graph Valid Tree
• [ ] Number of Connected Components
• [ ] Redundant Connection
• [ ] Word Ladder

12. Advanced Graphs

• [ ] Reconstruct Itinerary
• [ ] Min Cost to Connect All Points
• [ ] Network Delay Time
• [ ] Swim in Rising Water
• [ ] Alien Dictionary
• [ ] Cheapest Flights Within K Stops

13. 1-D Dynamic Programming

• [ ] Climbing Stairs
• [ ] Min Cost Climbing Stairs
• [ ] House Robber
• [ ] House Robber II
• [ ] Longest Palindromic Substring
• [ ] Palindromic Substrings
• [ ] Decode Ways
• [ ] Coin Change
• [ ] Maximum Product Subarray
• [ ] Word Break
• [ ] Longest Increasing Subsequence
• [ ] Partition Equal Subset Sum

14. 2-D Dynamic Programming

• [ ] Unique Paths
• [ ] Longest Common Subsequence
• [ ] Best Time to Buy/Sell Stock with Cooldown
• [ ] Coin Change II
• [ ] Target Sum
• [ ] Interleaving String
• [ ] Longest Increasing Path in Matrix
• [ ] Distinct Subsequences
• [ ] Edit Distance
• [ ] Burst Balloons
• [ ] Regular Expression Matching

15. Greedy

• [ ] Maximum Subarray
• [ ] Jump Game
• [ ] Jump Game II
• [ ] Gas Station
• [ ] Hand of Straights
• [ ] Merge Triplets to Form Target
• [ ] Partition Labels
• [ ] Valid Parenthesis String

16. Intervals

• [ ] Insert Interval
• [ ] Merge Intervals
• [ ] Non-overlapping Intervals
• [ ] Meeting Rooms
• [ ] Meeting Rooms II
• [ ] Minimum Interval to Include Query

17. Math & Geometry

• [ ] Rotate Image
• [ ] Spiral Matrix
• [ ] Set Matrix Zeroes
• [ ] Happy Number
• [ ] Plus One
• [ ] Pow(x, n)
• [ ] Multiply Strings
• [ ] Detect Squares

18. Bit Manipulation

• [ ] Single Number
• [ ] Number of 1 Bits
• [ ] Counting Bits
• [ ] Reverse Bits
• [ ] Missing Number
• [ ] Sum of Two Integers
• [ ] Reverse Integer

19. Sorting

• [ ] Bubble Sort
• [ ] Insertion Sort
• [ ] Selection Sort
• [ ] Merge Sort
• [ ] Quick Sort

🟢 Pillar 2: Architectural Patterns (Design Patterns)

Creational Patterns

• [x] Abstract Factory
• [x] Builder
• [x] Factory
• [x] Object Pool
• [x] Prototype
• [x] Singleton

Structural Patterns

• [x] Adapter
• [x] Bridge
• [x] Composite
• [x] Decorator
• [x] Facade
• [x] Flyweight
• [x] Proxy

Behavioral Patterns

• [x] Chain of Responsibility
• [x] Command
• [x] Interpreter
• [x] Iterator
• [x] Mediator
• [x] Memento
• [x] MVC
• [x] Null Object
• [x] Observer
• [x] State
• [x] Strategy
• [x] Template
• [x] Visitor

🟠 Pillar 3: Machine Coding & LLD Systems

Systems & Games

• [x] Parking Lot: machine_coding/systems/parking_lot/parking_lot.py
• [x] Elevator System: machine_coding/systems/elevator/elevator_management_system.py
• [x] Snake & Ladder: machine_coding/games/snake_ladder/PROBLEM.md
• [x] Tic-Tac-Toe: machine_coding/games/tic_tac_toe/PROBLEM.md
• [x] Instagram Feed: machine_coding/systems/instagram/PROBLEM.md
• [x] Cache System: machine_coding/systems/cache/PROBLEM.md
• [ ] Vending Machine: machine_coding/systems/vending_machine/PROBLEM.md

Distributed & Real-World

• [ ] Pub/Sub System: machine_coding/distributed/pub_sub/PROBLEM.md
• [ ] Job Scheduler: machine_coding/distributed/job_scheduler/PROBLEM.md
• [ ] Rate Limiter (distributed): machine_coding/distributed/rate_limiter/PROBLEM.md
• [ ] Workflow Orchestrator: machine_coding/distributed/workflow_orchestrator/PROBLEM.md
• [ ] E-Commerce Engine: machine_coding/real_world_systems/e_commerce_order_system/PROBLEM.md
• [ ] Ride-Sharing Service: machine_coding/real_world_systems/ride_sharing_service/PROBLEM.md
• [ ] CI/CD Pipeline: machine_coding/real_world_systems/ci_cd_pipeline/PROBLEM.md
• [ ] Distributed LLD: machine_coding/distributed/id_generator/snowflake.py

🔴 Pillar 4: Distributed Systems & Infrastructure

• [ ] Dockerized Cluster: infrastructure_challenges/dockerized_job_scheduler/PROBLEM.md
• [ ] Redis Rate Limiter: infrastructure_challenges/redis_rate_limiter/PROBLEM.md
• [ ] Socket Chat App: infrastructure_challenges/socket_chat_app/PROBLEM.md
• [ ] Circuit Breaker: infrastructure_challenges/resiliency/circuit_breaker.py
• [ ] Service Mesh Basics: infrastructure_challenges/envoy_proxy/SETUP.md

🏗️ Pillar 5: High-Level Design (HLD)

• [ ] KV Store: system_design_hld/architectures/distributed_storage/KV_STORE.md
• [ ] S3 Lite: system_design_hld/architectures/distributed_storage/S3_LITE.md
• [ ] Video Streaming (Netflix/YouTube): system_design_hld/architectures/streaming/VIDEO_STREAMING_SERVICE.md
• [ ] WhatsApp: system_design_hld/architectures/social_media/WHATSAPP.md
• [ ] Facebook Capacity: system_design_hld/architectures/social_media/FACEBOOK_CAPACITY.md
• [ ] URL Shortener: system_design_hld/architectures/utilities/URL_SHORTENER.md
• [ ] API Rate Limiter: system_design_hld/architectures/utilities/RATE_LIMITER.md
• [ ] Ticket Booking: system_design_hld/architectures/utilities/TICKET_BOOKING.md
• [ ] Search Engine: system_design_hld/architectures/utilities/ELASTICSEARCH_HLD.md
• [ ] Ad-Click Aggregator: system_design_hld/architectures/data_pipelines/AD_CLICKS.md

🧪 Testing Infrastructure

• [ ] Create tests/ directory structure mirroring dsa/, design_patterns/, machine_coding/
• [ ] Add conftest.py with shared pytest fixtures
• [ ] Add unit tests for DSA solutions (input → expected output)
• [ ] Add integration tests for machine coding systems
• [x] Set up CI pipeline to run make test and make lint