returnzero_
Your DashboardStudyPracticeMy SessionsPeer InterviewsArticles
Stateful API
  • Encode / Decode
  • In-Memory KV
  • Duplicate Files
  • KV Store
  • Monster Team Battle
  • GPU Credit Tracker v1
  • In-Memory DB · SQL
  • Auth Mgr · Sessions
  • KV Store · Thread-Safe
  • KV Store · Persistent
  • LRU Cache
  • Stack Samples
  • Sampling Profiler
  • Duplicate Files+
  • KV Store · Chunked
  • Dasher Payout
TTL / Expiry
  • Time-Based KV
  • Auth Mgr · TTL
  • Meeting Rooms
  • GPU Credit Tracker v2
Dependency Graph
  • Unix cd
  • Spreadsheet
  • Follow Graph
Resumable Iterator
  • IPv4 Iterator
  • Resumable Iterator
Grid / Graph
  • Disease Spread
  • N-ary Clusters
  • Vertical Order
  • Nested List Weights
  • Web Crawler
Other patterns
  • Semantic Version
  • Image Pipeline
  • Image Pipeline 2
  • Basic Calculator
  • Merge Intervals
  • LCA Family
  • Palindrome Deletions
  • Weighted Random
  • Kth Largest
  • Valid Parens
  • The Android App Template
  • Weather App
  • Notes App
  • Feature Flag SDK
  • Analytics / Logging SDK
  • Crash Reporter SDK
  • HTTP Client Library
  • Image Loading Library
  • Messenger App
  • Photo Gallery App
  • Music Player App
  • Doc Editor App
  • Newsfeed App
  • Ride-Sharing App
  • Autonomous Ride-Sharing App
Start a mock interview
returnzero_
HomePractice

Practice

What's new
New content

10 new coding challenges

Ten new multi-level coding challenges - Basic Calculator, LRU Cache, Merge Intervals Family, Lowest Common Ancestor Family, Binary Tree Vertical Order, Valid Palindrome With Deletions, Weighted Random Pick, Nested List Weights, Kth Largest Element, and Dasher Payout Engine.

Releasedyesterday
New content

17 new DSA practice questions

Seventeen new LeetCode-style practice questions across the DSA core concepts - arrays, binary search, bit manipulation, DFS, dynamic programming, graphs, greedy, hash maps, queues, recursion, sorting, trees, and union find - each with labeled examples, constraints, and a Solution Breakdown.

Releasedyesterday
Update

DSA pages aligned - canonical examples and Solution Breakdown

Every DSA core concept page now follows one structure - standalone canonical example pages, LeetCode-style problem formatting with labeled examples and constraints, a renamed Solution Breakdown section, and difficulty-ordered question sets.

Released2d ago
returnzero_

Full breakdowns, AI-guided practice on a live canvas, and mock interviews for Android system design and coding rounds.

StudyStudy overviewCodingAndroid System DesignBackend System Design
CompaniesAnthropicGoogleMetaStripeAmazonAll companies
ProductProblemsProduct tourPricingChangelogContact
AccountDashboardSettingsSign inCreate account
LegalPrivacyTermsRefunds
© 2026 returnzeroreturn 0