Question

I’m currently working on software for pedestrian navigation and the topic that is hard for me is to find the routing algorithm best suited for that task. I heard that A* is one of the algorithms actually used in that kind of software.

Could you suggest other algorithms that solve this problem? How do they compare regarding performances? How much memory and space do they require?

Thanks in advance for answers.

Answer 1

Well you could have a look at iterative deepening search. It’s a very smart approach to your problem in my opinion, but you risk to have a quite bad time complexity with respect to A* with a good heuristic since the algorithm is designed to make a complete exploration.

From wikipedia:

IDDFS combines depth-first search’s space-efficiency and breadth-first
search’s completeness (when the branching factor is finite). It is
optimal when the path cost is a non-decreasing function of the depth
of the node. The space complexity of IDDFS is O(bd), where b is the
branching factor and d is the depth of shallowest goal. Since
iterative deepening visits states multiple times, it may seem
wasteful, but it turns out to be not so costly, since in a tree most
of the nodes are in the bottom level, so it does not matter much if
the upper levels are visited multiple times.

And again, for what concerns time complexity:

The time complexity of IDDFS in well-balanced trees works out to be
the same as Depth-first search: O(bd).