yes, but none of them are that trivial... and if they were, then cheating wouldn't make much sense.
e.g. the coin change algorithm, I'm sure the distribution of answers was quite unique for anyone who tried solving it alone. same for even simple things like the pascal triangle.
But it's a moot argument as we need to do a real research (or ask coursera / Martin Odersky for the data, which I'm sure HN community will be happy to run some data mining on)
Actually I think some (many?) of the answers to the functional sets homework are that trivial in the sense that they're as short (or shorter) the the examples in the parent post. The only longer function was, I think, the one for which they provided a template implementation. So I think even that one would generate false positives somewhat easily.