Skip to content

Tracks

AI-assisted engineering Working with AI Agents System design Core systems Data and AI systems Coding Coding problems Code review On-call SQL

Practice

Paths Concept guides

FreeAd-supported

The plan adds AI feedback and removes ads.

Concept guides/Arrays and strings/Hash maps & sets

CodingArrays and strings

Hash maps & sets

Easy3 min read

Questions it teaches

Salted SHA-256 password hashEasy12 min First-time buyersEasy11 min First unique scanEasy12 min Latest employee recordsEasy12 min Find employees without badgesEasy11 min First submission per studentEasy11 min First unique playEasy10 min Rightmost unique valueEasy10 min

Related

Arrays and strings Searching and sorting Designing data structures Backtracking and games Dynamic programming Data and ML code Front-end code

Leads to: Searching and sorting

Sorting algorithms3 min Two pointers3 min

Leads to: Designing data structures

Queues, deques & ring buffers3 min Database deduplication3 min

Leads to: Backtracking and games

Recursion & backtracking3 min Game theory & Grundy3 min

Leads to: Dynamic programming

Dynamic programming: 2D & strings3 min Dynamic programming: 1D3 min

© 2026 Prep Room·From California·AI can make mistakes.

About Legal Contact Cookies Your privacy choices

Home Review Tracks Paths