The skill of not knowing

A real exam section never tells you which unit a question came from. The skill of not knowing is trainable: each mixed set below switches mechanism every challenge — a tracing question, then a spec implementation, then a bug hunt — with no headers. Your preparation ritual per question:

1. Classify in five seconds: is this predict-output, write-code, or fix-code? The response mode is the first decision, and misclassifying wastes minutes.
2. Name the mechanism: one mental sentence — "adjacent scan," "state machine," "removal discipline." If you cannot name it, the classification IS the exercise: slow down and inventory the nouns and verbs.
3. Answer in the mode required: MCQs here still demand the letter plus reasoning; coding items still demand passing tests.

The sets deliberately interleave difficulty — a speed-trap MCQ sits between two heavy implementations — because that is the exam's rhythm too.