Area Minimum Queries
On Problem Set One, we asked you to design two data structures for the area minimum query problem,
one running in time ⟨O(mn), O(min{m, n})⟩, the other in ⟨O(mn log m log n), O(1)⟩. It turns out that an
⟨O(mn), O(1)⟩-time solution is known to exist, and it's not at all what you'd expect.
Why they're worth studying: For a while it was suspected it was impossible to build an ⟨O(mn), O(1)⟩-
time solution to the area minimum query problem because there was no way to solve the problem using a
Cartesian-tree like solution – but then someone went and found a way around this restriction! Understand-
ing how the attempted lower bound works and how the new data structure circumvents it gives an interest-
ing window into the history of data structure design.
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