Compilare: main.cpp: In function 'int main()': main.cpp:49:34: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] 49 | sol[j - 1] = NULL; | ^~~~ main.cpp:65:34: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] 65 | sol[j - 1] = NULL; | ^~~~ main.cpp:87:28: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare] 87 | if(strlen(sol) != n) | ~~~~~~~~~~~~^~~~