Preorder traversal is a depth-first search algorithm for a binary search tree that first traverses the root, then the left subree, and then the right subtree. Its primary use is to create a copy of the tree.
The preorder algorithm can be described as follows:
Function Preorder(tree) return root + Preorder(left-subtree) + Preorder(right-subtree)
For the following binary search tree:
Preorder traversal provides the nodes in the following order: