Russell Eveleigh is using a Raspberry Pi Pico to demonstrate Dijkstra's algorithm visually with LEDs arranged as a map of the Cotswolds in England.

In such cases, the fastest known shortest-path algorithm doesn’t work. For decades, fast algorithms for finding shortest paths on negative-weight graphs have remained elusive.

Obviously, from x~>w there are two paths of equal length (x->y->w and x->z->w), both are a shortest path, from x to w. A question in my assignment is to determine if a shortest path is unique.