The problem can also be approached in a greedy way, based on the intuition that a camera in a location with more neighbours will cover more locations and thus minimise the number of cameras needed....

The problem can also be approached in a greedy way, based on the intuition that a camera in a location with more neighbours will cover more locations and thus minimise the number of cameras needed.

Here's the sketch of a greedy algorithm:

Letcity locations be the sequence of all nodes in thecity graph, ordered by descending degree.
Letcameras be the empty set.
Iterate overcity locations: for each node, if it's within 25 metres of a node incameras, skip it (because it's covered by a camera), otherwise add it tocameras.

Find a counter-example for the graph you created in part(b) to show that this greedy algorithm is not correct. Explain how you arrived at your counter-example. Give the output produced by the greedy algorithm, explaining why it's that output, and give the expected correct output.