/in/foo.cc: In function 'bool SPFA()':
/in/foo.cc:64:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<drt[t].size();i++)
               ~^~~~~~~~~~~~~~
/in/foo.cc:10:12: warning: 't' may be used uninitialized in this function [-Wmaybe-uninitialized]
 #define T t+2
            ^
/in/foo.cc:56:6: note: 't' was declared here
  int t;
      ^