Question

I’m learning about tree traversals and I can’t seem to find any clear rules for how DFS or BFS algorithms decide which path to take first. I’ve seen variations of left first or least first.

Is left taken as being first child in the list?
Does this mean that (for a given node) the depth of a vertex in a graph that is part of a cycle is taken using the leftward path?
Also doesn’t using a ‘least first’ rule make for a slower algorithm?
Thanks

Answer 1

Left is only meaningful for trees where the child nodes are oldered. Otherwise usually the author refers to first in the list of child nodes. Depth of a vertex is also not well defined in a graph that is not a tree, but if you refer to depth with respect to a given node that would usually be the shortest distance from the starting node.

I am not sure what does least first mean but if it refers to the key values of nodes and there is no ordering in the child nodes, finding the least will take more time of course.

Hope this helps.