Function diem_types::proof::position::inorder_to_postorder

pub fn inorder_to_postorder(node: u64) -> u64

Given node, an index in an in-order traversal of a perfect binary tree, what order would the node be visited in in post-order traversal? For example, consider this tree of in-order nodes.

     3
    /  \
   /    \
  1      5
 / \    / \
0   2  4   6

The post-order ordering of the nodes is:

     6
    /  \
   /    \
  2      5
 / \    / \
0   1  3   4

post_order_index(1) == 2 post_order_index(4) == 3