What is a Binary Tree?

This lesson is an introduction to binary trees and different types of binary trees.

Introduction

A tree in which each node can have a maximum of two children is known as a binary tree. You can refer to these children as the “left” and the “right” child. The figure below shows what a binary tree looks like:

%0 1 1 2 2 1->2 3 3 1->3 4 4 2->4 null 5 2->null
A binary tree

Types of Binary Trees

Complete binary trees

A complete binary tree is a binary tree in which all the levels of the tree are fully filled, except for perhaps the last level, which can be filled from left to right. The total number of nodes in a complete binary tree can be expressed as:

2htotal number of nodes2(h+1)12^{h} \leq \text{total number of nodes} \leq 2^{(h+1)}-1 ...