I shouldn't have to since the problem should have been written such that it works. You may put "using namespace std;", but I prefer not to.

Did you put "using namespace std;" ahead of your solution?

I can't even compile when using attempt due to this issue.
-isystem /runner/frameworks/cpp/ error: unknown type name 'string'; did you mean 'std::string'?
string sol1 = "[10, 3.0418396189]";

the sample tests represent at most 0,000001% of the performance requierment. They are just present for you to check the correctness of the basic requierments, not the performances.

EDIT: I missread your comment, but the result will be the same: the tape you found on this link is a rather small one and there are 10 tests for each size of tape (size up to several millions of characters for the performance tests (only one test) or ten thausend for the random tests)

It is only the "boilerplate" so it doesn't matter that much. I thought that every C++ guy knew that.

Edit: added.