Compilare: user.cpp: In member function ‘void Combinare::valid(int, int*, bool&)’: user.cpp:19:13: warning: unused variable ‘i’ [-Wunused-variable] int i; ^ user.cpp: In function ‘long long unsigned int solve2(long long unsigned int, long long unsigned int)’: user.cpp:143:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1 ; i <= nr ; i ++) ^ user.cpp:148:7: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(nr>1) ^ user.cpp:153:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 2 ; i < nr ; i ++) ^