Lecture 268:- Internal vs External Nodes of Strict Binary Tree

In a strict binary tree, also known as a full binary tree, all internal (non-leaf) nodes have exactly two children, and all leaf nodes (external nodes) have zero children. Therefore, in a strict binary tree:

1. Internal Nodes:
   • An internal node is a node that has two children.
   • All internal nodes in a strict binary tree have a left child and a right child.
2. External Nodes (Leaf Nodes):
   • An external node, also known as a leaf node, is a node that has zero children.
   • All leaf nodes in a strict binary tree do not have any children and are located at the edges of the tree.

Here's an example of a strict binary tree:

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         10       /    \      5      15     / \    /  \    3   8  12  20   / \         / \  2   4       18  25

In this strict binary tree, the internal nodes (10, 5, 15, 3, 8, 12, and 20) each have exactly two children (left and right), while the leaf nodes (2, 4, 18, and 25) do not have any children.

It's important to distinguish between internal and external nodes in a strict binary tree, as these distinctions play a significant role in various tree-based algorithms and operations. In strict binary trees, the structure is well-defined, and each internal node contributes to the hierarchy of the tree, ensuring that every internal node has exactly two children.