2, (15%) The network topology is shown on the right-hand side. Please use Dijkstra's algorithm to find the shortest path tree starting from node f. (a) Fill out the following table to show the process of Dijkstra's algorithm. (b) Draw the shortest path tree.
PS
1. The numbers beside the links represent the costs of the links.
2. D(b) denotes the lowest cost for the path from f to b at this step.
Step N' D(a) p(a) D(b) p(b) D(c) p(c) D(d) p(d) D(e) p(e) D(f) p(f)
0 1 - - 2 - - 3 - - 4 - - 5 - -