Tech Brushup

Your tech brushup — sharpen your instincts, one topic at a time.

Quick-reference guides for experienced engineers — templates, key problems, and the insights that matter under pressure.

Coding Patterns

Templates, top problems, full solutions, and the mistakes worth knowing before you're in the room.

Start Here Data Structures Two Pointer 11 problems Sliding Window 6 problems Binary Search 10 problems Trees 12 problems Dynamic Programming 12 problems Graphs 14 problems Stack 12 problems Linked Lists 14 problems Heap 8 problems Backtracking 12 problems Mixed Patterns 18 problems Intervals 4 problems Monotonic Stack 6 problems Trie 3 problems Union-Find 3 problems Concurrency 9 problems

System Design

Architecture patterns, distributed systems, failure scenarios, and the trade-offs you'll need to justify in the room.

Start Here Fundamentals Non-Functional Requirements System Design Layers Building Blocks Technology Selection Capacity Estimation What-If Scenarios Case Studies 7 problems Kafka Study Guide