"Pascal J. Bourguignon" <p...@informatimago.com> writes: > t...@sevak.isi.edu (Thomas A. Russ) writes: > > > > This will only work if there is a backpointer to the parent. > > No, you don't need backpointers; some cases have been mentionned in the > other answer, but in general: > > (defun parent (tree node) > (if (member node (children tree)) > tree > (some (lambda (child) (parent child node)) (children tree)))) > > Yes, the question wasn't about time complexity.
:-p Um, this is a recursive function. Inside PARENT, there is another call to PARENT. -- Thomas A. Russ, USC/Information Sciences Institute -- http://mail.python.org/mailman/listinfo/python-list
