foo.cc: In function ‘void Dijkstra()’:
foo.cc:49:30: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<infor>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   49 |                 for(int j=0;j<a[u].size();j++){
      |                             ~^~~~~~~~~~~~