Compilare: user.cpp: In function ‘void BFS(const int&)’: user.cpp:41:21: warning: variable ‘a’ set but not used [-Wunused-but-set-variable] pair <int, int> a = make_pair (0, 0); ^ user.cpp: In function ‘int main()’: user.cpp:108:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < P.size () - 1; ++i) { ^ user.cpp:110:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = i + 1; j < P.size (); ++j) { ^ user.cpp:127:15: warning: suggest parentheses around ‘+’ inside ‘>>’ [-Wparentheses] w = a + b >> 1; ^