To explore this, simulate the algorithm on the graph given, and record the vertices in r in the order that they are placed into the collecti on.

For the purpose of being able to reproduce a trace, please push the neighbors onto the stack (or

add to the end of the queue), in clockwise order starting at the node to directly to the north.

Depth first search (stack version)

r:

Stack:

Brea

dth first search (queue version)

r:

Queue:

2 4 6 9 10 13 15 16 17 18 2122 23 24 25 2 4 6 9 10 13 15 16 17 18 2122 23 24 25