Post-order traversal

Post-order traversal, also known as postfix traversal, is a way of visiting every node of a tree by recursively processing all of the subtrees first and then finally processing the root. It is a kind of tree traversal and a form of depth-first search. If the processing step is simply printing, a tree is printed as the first subtree, then the second subtree and so on up to the last subtree, followed by the root. For a binary tree the procedure is short: if the tree is null it returns, otherwise it processes the left subtree, then the right subtree, and finally prints the root. The Dictionary of Algorithms and Data Structures lists in-order traversal, pre-order traversal, level-order traversal and the Cupif-Giannini tree traversal as related entries, so post-order traversal is best understood as one of several standard orders for walking a tree.