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Binary tree traversal

Problem description :

Tree traversal (a.k.a tree search) is a form of graph traversal and refers to the process of visiting each node in a tree data structure, exactly once, in a systematic way. Such traversals are classified by the order in which the nodes are visited. Most commonly used traversal orders are the following :

  • In-order
  • Pre-order
  • Post-order

This post is a follow-up of Create a binary search tree in javascript. I recommend reading that first, as the following code uses the method from it.

Time complexity : O(n); n is the number of nodes in a tree

Pre-order traversal :

  1. Display the data part of root element (or current element)
  2. Traverse the left subtree by recursively calling the pre-order function.
  3. Traverse the right subtree by recursively calling the pre-order function
pre-order-min
Pre-order: F, B, A, D, C, E, G, I, H

Solution :


In-order traversal :

  1. Traverse the left subtree by recursively calling the in-order function
  2. Display the data part of root element (or current element)
  3. Traverse the right subtree by recursively calling the in-order function

Note: Elements are printed in the sorted order.

in-order-min
In-order: A, B, C, D, E, F, G, H, I

Solution :


Post-order traversal :

  1. Traverse the left subtree by recursively calling the post-order function.
  2. Traverse the right subtree by recursively calling the post-order function.
  3. Display the data part of root element (or current element).
post-order-min
Post-order: A, C, E, D, B, H, I, G, F

Solution :


ES6 :


References