For the C++ translation, the hidden tests do not compile.

The error shown is:

-isystem /runner/frameworks/cpp fatal error: 'boost/algorithm/string/join.hpp' file not found
#include <boost/algorithm/string/join.hpp>
^
1 error generated.

Thanks!

That's a very good observation! I assumed that the input is well formed, but I agree that nothing guaranties that. We can change the comparison:
if len(np.unique(view)) != 9:

to :
if not np.array_equal(np.sort(view), np.arange(1,10)):

so that now it checks only for the array [1,2,...,9]