stations.cpp: In function 'std::vector<int> label(int, int, std::vector<int>, std::vector<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<vec[s].size(); i++)
| ~^~~~~~~~~~~~~~
stations.cpp: In function 'int find_next_station(int, int, std::vector<int>)':
stations.cpp:79:1: warning: control reaches end of non-void function [-Wreturn-type]
79 | }
| ^
stations.cpp: In function 'std::vector<int> label(int, int, std::vector<int>, std::vector<int>)':
stations.cpp:13:10: warning: 'h' may be used uninitialized in this function [-Wmaybe-uninitialized]
13 | if (h%2==0) L[s]=coun;
| ~~~^~~
stations.cpp:13:18: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
13 | if (h%2==0) L[s]=coun;
| ^
/tmp/cc2iq4IW.o: In function `label(int, int, std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >)':
stations.cpp:(.text+0x317): undefined reference to `dfs(int, int)'
stations.cpp:(.text+0x3c3): undefined reference to `dfs(int, int)'
collect2: error: ld returned 1 exit status