Editing Priority queue (section)

=== Dijkstra's algorithm ===

When the graph is stored in the form of [[adjacency list]] or matrix, priority queue can be used to extract minimum efficiently when implementing [[Dijkstra's algorithm]], although one also needs the ability to alter the priority of a particular vertex in the priority queue efficiently.

If instead, a graph is stored as node objects, and priority-node pairs are inserted into a heap, altering the priority of a particular vertex is not necessary if one tracks visited nodes. Once a node is visited, if it comes up in the heap again (having had a lower priority number associated with it earlier), it is popped-off and ignored.