stations.cpp: In function 'void dfs(int, int)':
stations.cpp:14:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
14 | for (int i=0; i<v1[a].size(); i++)
| ~^~~~~~~~~~~~~
stations.cpp: In function 'std::vector<int> label(int, int, std::vector<int>, std::vector<int>)':
stations.cpp:42:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
42 | for (int i=0; i<v2.size(); i++)
| ~^~~~~~~~~~
stations.cpp: In function 'int find_next_station(int, int, std::vector<int>)':
stations.cpp:52:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
52 | for (int i=1; i<c.size()-1; i++)
| ~^~~~~~~~~~~
stations.cpp:68:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
68 | for (int i=1; i<c.size()-1; i++)
| ~^~~~~~~~~~~