- 1 current stop: learning
- 2 upcoming
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Finish after stop 5
Stop 1 of 5 · Review desk: five buckets
Trick to keep in mind+3 XP
The n log n limit binds comparers; counting sort uses keys as positions.
The lower bound comes from counting how many orderings a sort must tell apart when its only tool is comparing two items. A sort that never compares, and instead uses each key as an address or bucket, is outside that proof. The price is an assumption: the keys must be small whole numbers in a known range.
Read it once, then a question tests whether the trick stuck.