PHP 7 Data Structures and Algorithms

Post-order

In post-order traversal, the root node is visited last. The first left node is visited and then the right node. The principles of post-order traversal are as follows:

1. Traverse the left subtree by recursively calling the post-order function.
2. Traverse the right subtree by recursively calling the post-order function.
3. Display the data part of the root (or current node).

The preceding tree will have the output A, C, E, D, B, H, I, G, and F since it is traversed in a post-order way.

Now, let's implement the traversal logic in our BST class:

public function traverse(Node $node, string $type="in-order") { switch($type) {         case "in-order": ...