Preorder Traversal

Published Aug 10, 2022Updated Oct 26, 2022
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Preorder traversal is a depth-first search algorithm for a binary search tree that first traverses the root, then the left subtree, 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:

Binary Search Tree Diagram

Preorder traversal provides the nodes in the following order: 4, 2, 1, 3, 6, 5, 7.

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