Coding Prep

Topic-based, company-tagged problem sets with difficulty progression, timed drills, hints, solution walkthroughs, and weak-topic tracking — focused on the patterns your target companies actually ask.

Request a topic

Not covered yet? Describe it and we'll generate a worked guide, file it in the right section, and save it here for reuse.

Open the Coding Library

Browse all pattern guides and tagged problems, then open any topic for a worked solution.

Filter the Prep Library

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Coding Algorithms & Data Structures System Design AI / ML Context Engineering CAD & Mechanical Design Mock Interview Assessments Non-technical

Topics — tap to open the library guide

Arrays Strings Hash maps Two pointers Sliding window Trees Graphs BFS/DFS Dynamic programming Heaps Binary search Recursion Backtracking Greedy Intervals

Topic mastery

Arrays88%

9/10 solved

Strings74%

6/8 solved

Hash maps82%

5/6 solved

Trees64%

4/7 solved

Graphs · weak41%

2/8 solved

Dynamic programming · weak28%

1/9 solved

Heaps60%

3/5 solved

Intervals · weak38%

2/6 solved

Assigned & recent problems — tap for the full solution

Two Sum

Solved

Hash mapsEasy Northwind Labs· 1 attempts· best 6m

Course Schedule

Attempted

GraphsMedium Northwind Labs· 3 attempts· best —

Merge Intervals

Assigned

IntervalsMedium Helios Health· 0 attempts· best —

Coin Change

Attempted

Dynamic programmingMedium Northwind Labs· 2 attempts· best —

Word Ladder

Assigned

BFS/DFSHard Northwind Labs· 0 attempts· best —

Where this content comes from

For full transparency, problems, difficulty calibration, and company tags are curated and verified from these sources:

Curated company-tagged problem banksPublic competitive-programming archivesRecurring interview pattern librariesGlassdoor & levels.fyi reported questionsOppZen-authored drills