rejection sampling

Three parts, and most candidates finish one. The algebra fits on a line, the proof fits in three, and the part interviewers remember is the batch size at which the whole trick runs out of spare compute.

Lossless is a statement about one distribution, and quantization changes which one without raising any error. The answer separates the draft case from the target case, then shows two ways an FP8 deployment breaks exactness without touching the rejection rule.

The accept rule is one line. The residual distribution, the bonus token, rows that drafted fewer tokens and a test that can tell a lossless verifier from a subtly biased one are the rest of the grade.