stations.cpp: In function 'void dfs(int)':
stations.cpp:14:8: warning: left operand of comma operator has no effect [-Wunused-value]
14 | debug("dfs %d\n",x);
| ^~~~~~~~~~
stations.cpp: In function 'std::vector<int> label(int, int, std::vector<int>, std::vector<int>)':
stations.cpp:41:9: warning: left operand of comma operator has no effect [-Wunused-value]
41 | debug("%d ",i);
| ^~~~~
stations.cpp:42:8: warning: statement has no effect [-Wunused-value]
42 | debug("\n");
| ~^~~~~
stations.cpp: In function 'int find_next_station(int, int, std::vector<int>)':
stations.cpp:47:8: warning: left operand of comma operator has no effect [-Wunused-value]
47 | debug("qr %d %d ~",s,t); for(int i : c) debug("%d ",i); debug("\n");
| ^~~~~~~~~~~~
stations.cpp:47:23: warning: right operand of comma operator has no effect [-Wunused-value]
47 | debug("qr %d %d ~",s,t); for(int i : c) debug("%d ",i); debug("\n");
| ^
stations.cpp:47:48: warning: left operand of comma operator has no effect [-Wunused-value]
47 | debug("qr %d %d ~",s,t); for(int i : c) debug("%d ",i); debug("\n");
| ^~~~~
stations.cpp:47:64: warning: statement has no effect [-Wunused-value]
47 | debug("qr %d %d ~",s,t); for(int i : c) debug("%d ",i); debug("\n");
| ~^~~~~
stations.cpp:55:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
55 | for(int i=0;i<c.size();i++){
| ~^~~~~~~~~
stations.cpp:66:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
66 | for(int i=1;i<c.size()-1;i++){
| ~^~~~~~~~~~~
stations.cpp:71:1: warning: control reaches end of non-void function [-Wreturn-type]
71 | }
| ^