1.
| A | B | C | D | E |
| A | - | 15 | 19 | 25 | 20 |
| B | 15 | - | 15 | 15 | 25 |
| C | 19 | 15 | - | 22 | 11 |
| D | 25 | 15 | 22 | - | 18 |
| E | 20 | 25 | 11 | 18 | - |
The table shows the least distances, in km, between five hiding places, A, B, C, D and E.
Agent Goodie has to leave a secret message in each of the hiding places. He will start and finish at A , and wishes to minimise the total distance travelled.
- Use Prim's algorithm to find a minimum spanning tree for this network. Make your order of arc selection clear.
- Use your answer to part (a) to determine an initial upper bound for the length of Agent Goodie's route.
- Show that there are two nearest neighbour routes which start from A . State these routes and their lengths.
- State the better upper bound from your answers to (b) and (c).
- Starting by deleting B, and all of its arcs, find a lower bound for the length of Agent Goodie's route.
- Consider your answers to (d) and (e) and hence state an optimal route.