# Data Structure Interview Questions

Last updated on Feb 06, 2023
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A data structure is a user-preferred, specialized format to organize, manage, and store data for quick and efficient access and modification. A vast variety of Data Structure Interview Questions are also available on our website. Every data structure is designed to assemble and hold data to suit a specific purpose and preferably work with various algorithms. It renders multiple data elements regarding relationships and serves as the basis for Abstract Data Types. Implementing a data structure requires creating a set of procedure that produces as well as manipulate instances of that structure.

#### Benefits of Data structure

• With the help of Data structures, the desired data can be searched in a concise period from the vast amount of stored data like about data having an inventory of about 2 million items
• Multiple requests can be handled using the data structures like at a time processing the application of the thousands of user on the web browser.
• You can access the data from anywhere at any point in time.
• Data Structures helps in designing efficient algorithms.

Data Structures are used to organize the data in the memory of the computer in a very systematic manner to reduce the complexities of the task performed by the processor. As a result the performance of the computer or server increases. Here is the list of top algorithm interview questions which can help you to crack your interviews.

### Data Structures and algorithms interview questions

Here in this article, we will be listing frequently asked Data Structure Interview Questions and Answers with the belief that they will be helpful for you to gain higher marks. Also, to let you know that this article has been written under the guidance of industry professionals and covered all the current competencies.

Q11. Explain the difference between array and linked list?
1. An array is a collection of the elements of a similar data type. Linked List is an ordered collection of the elements of the same type and all the elements, with the help of pointer, are connected.
2. The array supports the Random Access. Here the elements can be accessed directly using their index, like arr[2] for the 3rd element, arr[1] for the 2nd element, arr[0] for the 1st element, etc. Linked List supports the Sequential Access. Here to access any element or node in a linked list, we have to sequentially traverse the complete linked list to reach to that element.
3. In an array, elements are stored consecutively in the memory. In a linked list, the new elements can be stored anywhere in the memory.
Q12. What is Stack and explain it's basic operations?

Stack comes under one of the types of Data Structure which is Linear Lists in which the data elements are stored sequentially. In Linear lists, the insertions and deletions of the data elements are easier.

Stack follow a "LIFO" rule which means 'Last In First Out' for storing and retrieving the data, i.e., Last data pushed into the stack will come out first.

There are two primary functions of Stack: Push() & Pop() for inserting and removing the data elements from the stack respectively.

Q13. What is Queue and how it is different from stack?

A Queue in the data structure is a linear structure which follows a particular order in which all operations to be performed. The order is First In First Out (FIFO) used in Queue.

S.no Stack Queue
1. Stack has only one end for inserting and deleting the data elements The queue has two terms, one for enqueuing the data and other for dequeuing the data elements.
2. There are no variants in Stack In queue, there are variants like a circular queue, priority queue, double ended queue
3. Stack uses only one pointer for its one end. Queue used 2 pointers for its two ends Rear and Front
3. Operations performed are Push() and Pop() Operations performed are enqueue() and dequeue()
Q14. What do you mean by Infix prefix and postfix notations?

Infix, Prefix, and Postfix are the there ways of writing the expressions.

S.no Infix notation Prefix notation Postfix notation
1. Infix notation is written as X + Y.The usual method of writing any mathematical expression is Infix notation. In this notation, the operators are written between their operands. Prefix notation is written as +XY.The operator comes before the operands. The evaluation of the prefix notation is from Left to Right Postfix notation is written as XY+.in this notation the operator enters after the operand. The review of the prefix notation is from Left to Right.
Q15. What do you mean by FIFO and LIFO?

LIFO:- LIFO stands for Last In First Out. In this method, the last data element entered will come out first.

FIFO:-FIFO stands for First in First Out. In this method, the data element entered first will come out first

Q16. Explain the difference between PUSH and POP?
S.no Push Pop
1. Push function is used for inserting the element into the stack The pop function is used for taking the component out from top of the stack
Q17. What will be the postfix expression for (A + B) * (C - D)?

(A+B)*(C-D)
STEP 1:-(AB+)*(CD-)
STEP 2:-AB+CD-*

Reading our vast question bank will make it easy for you to crack the data structure interview questions.

Q18. What do you mean by linked list also explain its types?

Linked List is an ordered collection of the elements of the same type and all the elements, with the help of this pointer, are connected.

There are three types of Linked List.

Q19. What do you mean by binary trees?

A Binary Tree comes under one of the types of data structure Non-Linear Lists. In this list, the data elements are not stored sequentially.

In a binary tree, the nodes are connected in a particular way which makes the search operation of the data very easy. Both the nodes have one or two child nodes, creating the branches of the tree. The child nodes on the left are called the left nodes and on the right are called the right nodes, and the top node is called the Root Node. The number of levels in the binary tree is called the height of the tree.

Q20. Whay do you mean by binary search tree?