O((n1 + n2) * log(n2)) looks better to me than O(n1 * n2), I don't know if I am missing something here. It does depend on the relative lengths of n1 and n2 though.

Technically, his solution is more optimal than the other solutions given. If you use qsort (O(n2 log n2) on the avg. case) on arr2, and bsort on arr2 for every element in arr1 ((O(n1 log n2)), then you have a time complexity of O((n1 + n2) * log(n2)), while the complexity of the other solutions are O(n1 * n2).

Every solution I've seen in here is O(n^2), safe to say I don't think there's a better way of doing it (You're calling qsort() once and then bsearch() on every iteration, not sure whether that's O(n^2) or not tbh)

How is this rated as the best solution when the time complexity isnt even optimal?

Initial value of *lg == -1 is not documented.

This shouldn't be a solution, although it's very clever how you gamed the system.

How did this get past the tests?

Thanks!

I redid some little things before publishing, but I could do that myself and you still get the points.

Appreciate your efforts! ( And the chance to read some C. That had been a while. :)

Ok, I changed the custom error messages for the random tests.

Any chance of custom error messages? ( See JavaScript for examples. ) The default messages probably won't give much ( useful ) information to solver.

This should be possible, accordig to the test framework documentation, but it mentions

[in] FormatString: (optional) printf-like format string
[in] ...: (optional) format string parameters

and I don't really know format strings, given that I don't really know C.

Because "Two strings may have more than one longest common subsequence. When this occurs, return any of them."

I made the changes as requested. However,I'm not sure why we can't just replace those three assertions with just
cr_assert_str_eq(actual,expected);

    cr_assert_str_eq(actual,expected);
    cr_assert_eq(isSubsequence(string2,expected),true);
    cr_assert_eq(isSubsequence(string1,expected),true);

I think that's incorrect.

length(actual) should be compared to length(expected), and isSubsequence(string1, actual), and string2, should be true.

It looks like you went off the C++ version, which had the subsequence tests wrong also. I fixed that. That one did compare lengths instead of values for actual and expected.

Could you fix this?