Compilare: user.cpp: In function ‘void calc_cost(int*)’: user.cpp:38:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<val.size();++j) { ^ user.cpp: In function ‘int main()’: user.cpp:46:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j; ^ user.cpp:47:15: warning: unused variable ‘cost’ [-Wunused-variable] long long cost=0; ^