Compilare: user.cpp: In function ‘int DFS(int, int)’: user.cpp:15:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < G[node].size(); i++) ~~^~~~~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:39:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < G[i].size(); j++) ~~^~~~~~~~~~~~~ user.cpp:45:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < G[i].size(); i++) ~~^~~~~~~~~~~~~ user.cpp:33:17: warning: ‘a’ is used uninitialized in this function [-Wuninitialized] int a,b; ^ user.cpp:33:19: warning: ‘b’ is used uninitialized in this function [-Wuninitialized] int a,b; ^