6 A mountain ridge separates two populated areas. Networks representing roads connecting the villages in each area are shown below. The numbers on the arcs represent distances in kilometres.
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There is also a mountain road of length 15 kilometres connecting C to Z .
- A national bus company needs a route from A to X .
- Use Dijkstra's algorithm on the complete network, including CZ, to find the shortest route from A to X . Give the route and its corresponding distance.
- Would it need fewer computations to use Dijkstra's algorithm on the network for villages A to F to find the shortest route from A to C, and then use Dijkstra's algorithm on the network for villages U to Z to find the shortest route from Z to X? Give a brief justification for your answer.
- The local council needs to discover which roads it should keep clear of snow during the winter to keep all the villages connected, and the corresponding total length of road.
- Use Kruskal's algorithm on the network for villages A to F to find a minimum connector for \(\{ \mathrm { A } , \mathrm { B } , \mathrm { C } , \mathrm { D } , \mathrm { E } , \mathrm { F } \}\). Show your use of the algorithm. Draw your minimum connector.
- Use Prim's algorithm on the network for villages U to Z to find a minimum connector for \(\{ \mathrm { U } , \mathrm { V } , \mathrm { W } , \mathrm { X } , \mathrm { Y } , \mathrm { Z } \}\), starting at U . Show your use of the algorithm. Draw your minimum connector.
- What is the total length of road that the council must keep clear of snow?