Edexcel FD1 2019 June — Question 2

Exam BoardEdexcel
ModuleFD1 (Further Decision 1)
Year2019
SessionJune
TopicShortest Path

2. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{162f9d72-84a4-4b1a-93cf-b7eeb7f957ae-03_663_1421_203_322} \captionsetup{labelformat=empty} \caption{Figure 1
[0pt] [The total weight of the network is 370]}
\end{figure} Figure 1 represents a network of corridors in a building. The number on each arc represents the length, in metres, of the corresponding corridor.
  1. Use Dijkstra's algorithm to find the shortest path from A to D, stating the path and its length. On a particular day, Naasir needs to check the paintwork along each corridor. Naasir must find a route of minimum length. It must traverse each corridor at least once, starting at B and finishing at G .
  2. Use an appropriate algorithm to find the arcs that will need to be traversed twice. You must make your method and working clear.
  3. Find the length of Naasir's route. On a different day, all the corridors that start or finish at B are closed for redecorating. Naasir needs to check all the remaining corridors and may now start at any vertex and finish at any vertex. A route is required that excludes all those corridors that start or finish at B .
    1. Determine the possible starting and finishing points so that the length of Naasir's route is minimised. You must give reasons for your answer.
    2. Find the length of Naasir's new route.