The description is still incomplete and the task is still not novel at all. Please, don't resolve issues for no reason.

resolved, thanks

Yes indeed, it will be better this way, thanks

• Sample tests are missing an include for std::vector
• random header's functionality should be used instead of std::srand and std::rand
• Description says nothing about duplicate elements handling
• Pretty much a duplicate of this kata

Not sure about that, but there's no need for vector of vectors to store solutions. Simply create a copy of the generated vector, pass it to your solution to get the expected value, and then pass the original vector to solver function. At that point, the user can modify anything they want, the expected answer won't change.

fixed(at least i hope so)

Random tests are vulnerable to input modification. Compute the expected value first.

• Non-standard header files should not be used
• Initial solution shouldn't include using namespace std, and the tests shouldn't rely on the user's solution to include it
• The input type should be std::vector<unsigned> and the output type should be unsigned
• Nothing's said about duplicate numbers and how they should be handled, e.g. what range is {1, 2, 2, 2, 1, 1} supposed to represent?
• No random tests

I'm pretty sure this is a duplicate as well.