Postordering

Postordering is a traversal algorithm used on tree data structures. In a postorder traversal, for any given node, the algorithm first recursively visits all of the node's children from left to right, and only after all children have been visited does it visit the node itself. This means that a node is processed after all of its descendants have been processed.

The name "postorder" comes from the fact that the node is processed *after* its children, or "post" the children's processing. This is in contrast to preorder traversal, where the node is processed *before* its children, and inorder traversal, where the node is processed *between* its left and right children (for binary trees).

Postorder traversal is particularly useful in certain applications. For example, when deleting a tree, postorder traversal is often used to ensure that child nodes are deleted before their parent nodes. This prevents memory leaks or dangling pointers. It is also employed in tasks such as generating postfix expressions from abstract syntax trees. The order in which nodes are visited ensures that operations are applied to their operands before the operands themselves are processed further.