90-Day Tech Interview Prep Plan

Ninety days is enough time to build genuine depth rather than surface familiarity. This plan is appropriate for engineers preparing from a cold start or after a significant career gap.

Month 1: Foundation Breadth

Weeks 1-4: Cover all core data structures. Arrays, linked lists, trees, graphs, heaps, tries, union-find. Solve 4-5 problems per data structure to internalize patterns. Use the 'explain while solving' method to simulate interview conditions.

System design: read Designing Data-Intensive Applications (Kleppmann) or at least the first six chapters. This gives you the vocabulary for distributed systems discussions. Keep a 'system design notebook' of key patterns: caching strategies, database choices, load balancing.

Month 2: Algorithm Depth

Weeks 5-8: Dynamic programming (3 weeks), then advanced graph algorithms (Dijkstra, Bellman-Ford, Floyd-Warshall, topological sort, SCC). DP is the highest time investment with the highest return at senior levels.

Mock interviews: 2 per week starting in week 6. Aim for a mix of companies (one medium-difficulty company, one hard-difficulty company). Track your scoring: what rubric dimensions are you weak on?

Month 3: Company-Specific and Polish

Weeks 9-12: Pick your top 3 target companies. Study their specific patterns from LeakCode, Blind, and Glassdoor. Solve problems from their question bank. Understand their system design vocabulary (AWS services for Amazon, YouTube's system for Google).

Final two weeks: full simulation. Interview day simulations with two coding + one system design + one behavioral per day. Gradually taper practice intensity in the final week to avoid burnout. Sleep and recovery matter for performance.

Tracking and Adjusting

Keep a spreadsheet of every problem solved: date, topic, difficulty, whether you got it without hints, time taken. Review problems you got wrong on days 30, 60, and 89. Spaced repetition is more effective than re-solving easy problems.

If month 2 reveals a major gap (e.g., you consistently fail DP), extend month 2 by one week and compress month 3 by one week. The plan is a framework, not a fixed schedule.

Browse Target Company Questions

See what your target companies are currently asking.

Browse All Companies