Python Data Structures and Algorithms

Post-order traversal and postfix notation.

Postfix or reverse Polish notation (RPN) places the operator after its operands, as in 3 4 +. As is the case with Polish notation, there is never any confusion over the precedence of operators, so parentheses are never needed: 4 5 + 5 3 - *.

In this mode of traversal, you would visit the left sub-tree, the right sub-tree, and lastly the root node.

The post-order method is as follows:

    def postorder(self, root_node):         current = root_node         if current is None:             return         self.postorder(current.left_child)         self.postorder(current.right_child)         print(current.data)