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":"2020-03-23T12:57:26.966Z","handle":"2020-03-23T12:57:26.966Z","cache_start":"2020-03-23T12:57:26.972Z","read_cases":"2020-03-23T12:57:27.084Z","judge":"2020-03-23T12:57:27.086Z","done":"2020-03-23T12:57:28.227Z"}