I had a similar question about the Topology at maelstrom challenge: request to implement topology and then ignore it is very confusing.. It is impossible with the cluster of the offered size (25 nodes), given grid topology (no direct messages, 5x5) and the latency constraints of 100ms min with n^2 to achieve required latencies.
It looks like some details are just undersaid and omitted. For interviews even for good. But that’s totally confusing.