4 The network below represents a treasure trail. The arcs represent paths and the weights show distances in units of 100 metres. The total length of the paths shown is 4200 metres.
\includegraphics[max width=\textwidth, alt={}, center]{cdad4fbe-4b94-4c8f-bb42-24d20eeaab4d-4_681_1157_450_459}

1. Apply Dijkstra's algorithm to the network, starting at \(A\), to find the shortest distance (in metres) from \(A\) to each of the other vertices. Alex wants to hunt for the treasure. His current location is marked on the network as \(A\). The clues to the location of the treasure are located on the paths. Every path has at least one clue and some paths have more than one. This means that Alex will need to search along the full length of every path to find all the clues.
2. Showing your working, find the length of the shortest route that Alex can take, starting and ending at \(A\), to find every clue. The clues tell Alex that the treasure is located at the point marked as \(H\) on the network.
3. Write down the shortest route from \(A\) to \(H\). Zac also starts at \(A\) and searches along every path to find the clues. He also uses a shortest route to do this, but without returning to \(A\). Instead he proceeds directly to the treasure at \(H\).
4. Calculate the length of the shortest route that Zac can take to search for all the clues and reach the treasure.