foo.cc: In function 'int swp(int*, int*)':
foo.cc:19:48: warning: no return statement in function returning non-void [-Wreturn-type]
   19 | int swp(int *a,int *b){int tmp=*a;*a=*b,*b=tmp;}
      |                                                ^
foo.cc: In function 'void spfa(int)':
foo.cc:35:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<node>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   35 |         for(int i=0;i<map[T].size();i++){
      |                     ~^~~~~~~~~~~~~~

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