Understanding the stateless preorder traversal pattern

Preorder traversal follows the node-left-right processing sequence, where we process a node as we enter it and repeat the process recursively for both its left and right subtree. Because a node is processed before its left and right subtrees, the preorder traversal is ideal for solving problems where data must be processed and passed down from parent to child nodes. The child nodes then process the data they receive from their parent and pass it down to their children.

There are two ways to pass data between nodes. One requires maintaining some shared state, while the other is completely stateless. The choice between these options depends on the problem. The stateless preorder traversal is the regular preorder traversal technique that passes data from child nodes to the parent node instead of sharing a single copy between nodes.