Compilare: user.cpp: In function ‘void build_1(int, int)’: user.cpp:18:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( i = 0; i < nei[n].size(); i ++ ) { ^ user.cpp:26:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if ( i < nei[n].size() ) { ^ user.cpp: In function ‘void build_2(int, int)’: user.cpp:38:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( i = 0; i < nei[n].size(); i ++ ) ^ user.cpp: In function ‘int main()’: user.cpp:46:15: warning: unused variable ‘j’ [-Wunused-variable] int n, i, j, a, b; ^