Final answer:
Post-order traversal is a depth-first traversal method for binary trees, where the left and right subtrees are visited before the root node. The pseudo code provides a recursive function that visits each node exactly once, leading to an O(n) running time.
Step-by-step explanation:
Post-order traversal is a type of depth-first traversal that is used primarily in binary trees. This traversal method follows the pattern of visiting the left subtree, then the right subtree, and finally processing the root node of the binary tree. It is commonly used for tasks where you need to work with the children nodes before the parent, such as when deleting nodes in a tree or evaluating expression trees.
Pseudo Code for Post-order Traversal
function postOrderTraversal(node)
if node is not null then
postOrderTraversal(node.left)
postOrderTraversal(node.right)
visit(node)
end function
The running time of post-order traversal is O(n) where n is the number of nodes in the tree. This is because each node is visited exactly once during the traversal process.