stations.cpp: In function 'void dfs(int)':
stations.cpp:15:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
15 | for(int i=0;i<w[x].Q.size();i++)
| ~^~~~~~~~~~~~~~
stations.cpp: In function 'std::vector<int> label(int, int, std::vector<int>, std::vector<int>)':
stations.cpp:31:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
31 | for(int i=0;i<u.size();i++)
| ~^~~~~~~~~
stations.cpp:42:1: warning: no return statement in function returning non-void [-Wreturn-type]
42 | }
| ^
stations.cpp: In function 'int find_next_station(int, int, std::vector<int>)':
stations.cpp:45:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
45 | for(int i=0;i<c.size();i++)
| ~^~~~~~~~~