How to evaluate efficiency...

[DieterPi]

A question about setting up exercises on efficiency...

Say I want to make a exercise on binary search, how could I make a test plan that checks if a binary search has been used? Like testing for the number of comparisons.

I know I can set a time limit combined with a 'bit' test case to force efficient solutions. But setting that up feels like trail-and-error.. (what time limit do I need, what size of test case do I need ...)

It would be great if I could construct a (custom) testcase that checks for the number of comparisons. How should I handle this idea?