The Expert 303

The core 150 teaches you to recognise a pattern. This is the second pass — the same twenty patterns, weighted to Medium and Hard, for when recognition is no longer the bottleneck and execution under pressure is.

Overlap with the core sheet is deliberate. A problem worth solving in month one is often worth re-solving in month four, under a clock, without the editorial.

Every problem here is a free, public LeetCode problem, checked against LeetCode itself when this page was built — no premium-only problems, no dead links. We don't host the problems; we decide the order and track what you've done.