¿Cómo podemos implementar el algoritmo de Prim rápidamente en los concursos de programación?

Puede usar en C ++ STL.

  #include 
 #include 
 #include 
 #incluye 
 #include 
 #include 

 usando el espacio de nombres estándar;

 typedef vector  vi;
 typedef vector  vvi;
 typedef pair  ii;
 typedef vector  vii;
 typedef vector  vvii;
 #define all (c) (c) .begin (), c.end ()
 #define sz (c) int ((c) .size ())
 #define tr (c, i) para (typeof ((c) .begin ()) i = (c) .begin (); i! = (c) .end (); ++ i)
 #definir presente (c, x) ((c) .find (x)! = (c) .end ())
 #define cpresent (c, x) (find (all (c), x)! = (c) .end ())


 vii Prim_MST (vvii y G) {
   int n = sz (G);
   vector  D (n, INT_MAX), padre (n, 0);
   vector  abarcado (n, falso);
   establecer  Q;
   vii mst_edges;
   D [0] = 0;
   Q.inserción (ii (0, 0));
   while (! Q.empty ()) {
     ii arriba = * Q.begin ();
     Q.erase (Q.begin ());
     abarcado [top.second] = verdadero;
     int v = top.second;
     si (v! = 0) {
       mst_edges.push_back (ii (padre [v], v));
     }
     tr (G [v], it) {
       int v2 = it-> first, cost = it-> second;
       if (D [v2]> cost &&! spanned [v2]) {
         if (presente (Q, ii (D [v2], v2))) {
           Q.erase (Q.find (ii (D [v2], v2)));
         }
         D [v2] = costo;
         Q.insert (ii (costo, v2));
         padre [v2] = v;
       }
     }
   }
   return mst_edges;
 }

 int main (nulo) {
   fstream inFile;
   inFile.open ("temp.txt");
   int n, m;
   inFile >> n >> m;
   vvii G (n);

   int u, v, costo;
   while (inFile >> u >> v >> costo) {
     G [u-1] .push_back (ii (v-1, costo));
     G [v-1] .push_back (ii (u-1, costo));
   }

   cout << "Los bordes MST son" << endl;
   vii mst_edges = Prim_MST (G);
   tr (mst_edges, it) 
     cout < first + 1 << "," < second + 1 << endl;
 }