Breadth First Traversal

These three are certainly not the only possible traversal orders. Another very natural traversal order is ``level by level'' - the root is processed first, all its children are processed next, then all of their children, etc. down to the bottom level. This is called breadth first traversal. In the above example, it would process nodes in the order: A-B-C-D-E-F. It is not difficult to write a breadth-first traversal, but is not quite as simple as the traversal orders just described.