foo.cc: In function 'bool dfs(int)':
foo.cc:18:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<g[u].size();i++)
                  ^
foo.cc: In function 'int main()':
foo.cc:62:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d",&n,&m);
                        ^

自豪的采用 HydroJudger 进行评测(github.com/hydro-dev/HydroJudger)

{"receive":"2020-03-23T12:28:25.170Z","handle":"2020-03-23T12:28:25.170Z","cache_start":"2020-03-23T12:28:25.177Z","read_cases":"2020-03-23T12:28:25.292Z","judge":"2020-03-23T12:28:25.293Z","done":"2020-03-23T12:28:26.530Z"}