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

Here's a shorter version iluxa's original answer. It runs exactly the same node manipulation and printing steps, in exactly the same order — but in a simplified manner [1]:

void traverse (Node n) {
  while (n) {
    Node next = n.left;
    if (next) {
      n.left = next.right;
      next.right = n;
      n = next;
    } else {
      print(n);
      n = n.right;
    }
  }
}

[1] Plus, it even works when the tree root node has no left child.