Looking for fast algorithm to find distance between two nodes in binary tree

Question

How do I find the distance between two nodes in a binary tree? Equivalently, what algorithms are there for finding the most recent common ancestor (lowest common ancestor)

Answer 1

Finding the common ancestor is almost certainly the easier task. This is a pretty simple one: start from the root of the tree, and descend the tree until you reach a node where you would have to descend to different children to get to the two nodes in question. That node is the common parent (assuming the tree contains both nodes, of course).