Print binary tree in BFS fashion with O(1) space

Question

I was wondering if it\'s possible to print a binary tree in breadth first order while using only O(1) space?

The difficult part is that one have to use additional sp

Answer 1

I know that this is strictly not an answer to the question, but visiting the nodes of a tree in breadth-first order can be done using O(d) space, where d is the depth of the tree, by a recursive iterative deepening depth first search (IDDFS). The space is required for the stack, of course. In the case of a balanced tree, d = O(lg n) where n is the number of nodes. I honestly don't see how you'd do it in constant space without the backlinks suggested by @Charlie Martin.