/in/foo.cc: In function 'int swp(int*, int*)':
/in/foo.cc:19:61: 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; }
      |                                                             ^
/in/foo.cc: In function 'void spfa(int)':
/in/foo.cc:35:27: 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++) {
      |                         ~~^~~~~~~~~~~~~~~