Last Updated: Mar 27, 2024

# Difference Between Stack and Tree

## Introduction

Acing a tech interview begins months, if not years before the interview takes place. There's a long list of required topics, such as operating systemsdatabases, and system design. However, one of the most important topics among all is data structures.

Data structures are just a way of storing data so that it may be accessed and modified quickly. There are many sorts of data structures, each of which is appropriate for a specific application. We'll look at two of these DS today: Stack and Tree. So let's get this party started.

## Stack

Stack is a linear data structure with three major operations- PUSH, POP, and TOP for Insertion, deletion, and retrieving the top element, respectively.

Consider an empty long rectangular box containing some books. Suppose you bought a new book and put it in the box on top of the stack of books you already had. Which book do you think you'll be able to get out of the box first? It's, of course, the last book you inserted. This is what a stack looks like. The last element you inserted will be the first to pop out of the stack, i.e., it follows the LIFO(Last in, first out) property.

Diagrammatic Representation of a Stack

## Tree

tree is a nonlinear data structure that can be best described recursively. It consists of NODESâ€”such that.

• Each tree has a root node that can have zero or more child nodes.
• Each child node can have one or more children, and so forth.
• The node which has no child nodes is called a leaf node.

Every node has a DATA element and a list of pointers to child nodes.

Some special types of trees are:

1. Binary Tree: Binary Tree is a tree where each node can have a maximum of two children â€˜LEFTâ€™ and â€˜RIGHTâ€™.

Example

1. Binary Search Tree: A binary search tree is a binary tree in which each node's value is greater than all nodes values in the left subtree and smaller than all nodes values in the right subtree.

Example

1. Balanced and Unbalanced Tree: A balanced tree ensures O(log N) time for insertion and deletion. Two common examples of balanced trees are the Red-Black tree and the AVL tree. And the trees which are not balanced are called unbalanced trees.
2. Complete Binary Tree: Itâ€™s a binary tree where each level contains the maximum number of nodes that a level can have except the last layer, which is filled from left to right.

Example

1. Full Binary Tree: A full binary tree is a tree in which each node has either zero or two child nodes.

Example

1. Perfect Binary Tree: This is both complete and full.

Example

## Difference between Stacks and Trees

### What type of data structures(Linear or Non-Linear) are Stacks and Trees?

Stack is a Linear Data Structure, while Tree is a Non-Linear Data structure.

### What is the insertion complexity for a node in a binary tree and stack?

The insertion complexity of a binary tree in the worst case is O(n) where n is the number of nodes, whereas the insertion complexity of an element in stack is O(1) which is constant.

## Conclusion

Weâ€™ve discussed what stack and tree data structures are and whatâ€™s the difference between them. Visit Coding Ninjas Studio to read more amazing blogs about data structures and algorithms.

Coding Ninjas has also released a new Mock test series for cracking top tech companies.

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Do check out The Interview guide for Product Based Companies as well as some of the Popular Interview Problems from Top companies like Amazon, Adobe, Google, Uber, Microsoft, etc. on Coding Ninjas Studio.

You can also consider our Mern Stack Course to give your career an edge over others.

Thanks for reading. I hope you've learned a lot from this blog.

Topics covered
1.
Introduction
2.
Stack
3.
Tree
4.
Difference between Stacks and Trees
4.1.
List of Top Stacks Questions
4.2.
List of Top Trees Questions
5.