Write a non-recursive traversal of a Binary Search Tree using constant space and O(n) run time

Question

This is not homework, this is an interview question.

The catch here is that the algorithm should be constant space. I\'m pretty clueless on how to d

Answer 1

It's a binary search tree, so every node can be reached by a series of right/left decision. Describe that series as 0/1, least-significant bit to most-significant. So the function f(0) means "the node found by taking the right-hand branch until you find a leaf; f(1) means take one left and the rest right; f(2) -- that is, binary 010 -- means take a right, then a left, then rights until you find a leaf. Iterate f(n) starting at n=0 until you have hit every leaf. Not efficient (since you have to start at the top of the tree each time) but constant memory and linear time.