["Followup-To:" header set to comp.lang.python.] On Wed, 18 May 2011 21:09:15 +0200, Raymond Wiker <raw@RAWMBP-2.local> wrote: : > In the sense that the tree itself is a stack, yes. But if we : > consider the tree (or one of its branches) to be a stack, then : > the original claim becomes a tautology. : : No, the tree is not a stack, but the chain of parent pointers : from a particular node may be considered as a stack that records the : path taken to reach the current node.
That is one of its branches, yes, path from root towards leaf. It is part of the data structure, and you don't travers a data structure without using the datastructure. : > But you do have a point. Keeping a stack of nodes on the path : > back to root is a great deal simpler and cheaper than a call : > stack, and not really a significant expense in context. : : For this particular operation, possibly. For other tree : operations, a single parent pointer may not be sufficient. Que? What tree operations do you have in mind? We have covered all the standard textbook tree walks by now. -- :-- Hans Georg -- http://mail.python.org/mailman/listinfo/python-list