graph priority first traversal

Priority First Traversal of a Graph

Set-Up:

Each vertex of the graph has a status variable which has one of three values: {WAITING, READY, VISITED}
A priority queue called readyPQ has been created and initialized to an empty state.



Procedure PriorityFirstTraversal
{

  Set the status of each vertex to WAITING ;
  For each node V in the graph
    If    status(V) is WAITING
    Then  VisitComponentOf(V) ;
}


Iterative Version of Procedure VisitComponentOf

Procedure VisitComponentOf(vertex V) 

{ /* Begin Procedure VisitComponentOf */

   Place V in readyPQ ;
   While ( readyPQ is not empty )
   { /* begin while-loop */
      
      Let X be the highest priority element of readyPQ;
      Remove X from readyPQ;
      Process X ;
      Set status(X) = VISITED;

      For each N adjacent to X with status(N) = WAITING
        { 
           Set status(N) to READY;
           Place N in readyPQ;
        }

   } /* end while-loop */
} /* End Procedure VisitComponentOf */