## Introduction to Data Structure Interview Questions and Answers

There has various kind of data available in a current digital system, all those are sometimes are very structural or UN structural. Handling that kind of data are maximum time very challenging and there have a big chance of loss of data at any time if people not keeping those data in a proper manner. Now data structure is mainly used to maintain require the structure of the data anytime for better and efficient use without big risk of losing important data. There have varieties kind of data structure available in the market, and all of them following some of their unique characteristics, so they are always be a possible solution for different applications whichever available in the market. Anytime some of the data structure is very much specifically using for one or more individual task for their completion. For example, for designing or preparing proper database structure (whether it is relational or not relational that does not matter) organizer normally following B-Trees data structure.

B-Tree data structure properly provides a full presentation of maintaining tables or relational database structure which is using huge for any kind of application, and currently without this kind of database structure application not able to fulfill their requirements properly. Same way if people willing to identify some specific table by lookup identifier, the best way for the same to use a hash table where compiler implementation is always preferable. In a top view, two kinds of data structure normally used, one is Linear (Array, Stack, Queue, Linked list) and another one is Non-Linear (Trees or Graph).

Now, if you are looking for a job which is related to Data Structure then you need to prepare for the 2020 Data Structure Interview Questions. It is true that every interview is different as per the different job profiles. Here, we have prepared the important Data Structure Interview Questions and Answers which will help you get success in your interview.

In this 2020 Data Structure Interview Questions article, we shall present 10 most important and frequently used Data Structure interview questions. These questions will help students build their concepts around Data Structure and help them ace the interview.

### Part 1 – Data Structure Interview Questions (Basic)

This first part covers basic Data Structure Interview Questions and Answers.

#### Q1. Provide some more details on various actions or operations performed by different data structure?

**Answer:**

Different kind of normal activities done by data structure like Insertion, Deletion, Traversal, Searching and Sorting.

Any kind of adding a new data item to a specific collection of a data item can considering as Insertion activity for the data structure.

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Same deletion existing data items from the define item collection can be considered as Deletion activity for the data structure.

Maintaining one common and single approach to fetch all the data item exactly once and processed the same success can be considered as Traversal.

Find out exact data item inside an entire collection of the data item if that specific data item already exists in that specific collection of data, it is considering as a searching mechanism of the data structure.

Now one of the big requirement of maintaining proper ordering of data item in a specific collection. It always maintained proper sorting by ascending or descending data in case of a numeric data item in the collection or ordering data based on a sequence of alphabetically in case of non-numeric data.

#### Q2. Explain different between Linked List and Array in case of data structure?

**Answer:**

There is a lot of structural difference between Linked List and Array, some of the key differences are mentioning below:

- Linked List is always in dynamic in case of defining size, where in case of Array sizing need to be initialized first.
- For performing an insert or delete of any data item for the collection like Linked List is very easy to do, whereas it too costly in case of doing inserting or deleting activity for an array of an element.
- Some time for critical kind of application random access is required on the specific collection data item, the Linked list never support this kind of random access utility, whereas Array of element allowing random access on a specific data item.
- In the case of memory utilization, the linked list always needed some extra spaces for a specific pointer considering each element append inside the linked list. But an array is normally taken constant memory space based on the size defined at the time of initialization does not consider whether that memory has been used or not any time by the application.

Let us move to the next Data Structure Interview Questions And Answers.

#### Q3. Explain about the stack in details and how it can be used in case of data structure?

**Answer:**

A stack is one the big example of a linear data structure. It normally followed one of the data structure most popular characteristics like maintain order based on first in first out (FIFO) or last in last out (LILO) utility. Stack normally following some basic kind of operation like Pop, Push or Peek.

The application which can be done by stack are mentioning below:

By using stack conversation from Infix to Postfix is very easy.

In expression evaluation by the stack is too popular in case of postfix.

A stack is eventually helpful in case of reversing String.

#### Q4. Provide details explanation regarding queue, explain main difference in between queue and stack, and give more details regarding implementation of queue.

**Answer:**

This is the basic Data Structure Interview Question which is asked in an interview. A queue is again one of the popular examples of linear structure which followed by first in first out structure properly. Basic operations which are using by the queue are Front, Enquequ, Dequequ, and rear.

The main difference between stack and Queue that are highlighted everywhere is stack normally following to remove one item which is most recently added. Whereas queue always removing that item which is least recently added. Both of them can be easily integrated by using arrays and linked list.

#### Q5. Explain about different notation like infix, prefix or postfix in the data structure?

**Answer:**

Infix Notation:

A*(B+C)/D

Postfix Notation:

ABC+*D/

Prefix Notation:

/*A+BCD

### Part 2 – Data Structure Interview Questions (Advanced)

Let us now have a look at the advanced Data Structure Interview Questions And Answers.

#### Q6. Define Linked List in details and explain varieties types available in Linked List?

**Answer:**

Three types, Singly Linked List, Doubly Linked List, Circular Linked List.

#### Q7. Indicating details of the data structure in case of generating a graph by using BFS and DFS?

**Answer:**

The queue for BFS and Stack for DFS.

Let us move to the next Data Structure Interview Questions And Answers.

#### Q8. Is implementing of double link possible in any case of define one variable which actually holding one single pointer in every node?

**Answer:**

Yes.

#### Q9. Provide a proper mechanism for implementing require queue by using a stack in the data structure?

**Answer:**

A stack can be implemented by two Queues.

#### Q10. Explain about LRU cache and give full details of using which suitable data structure should be used for the same?

**Answer:**

Queue and Hash both of these data structure can be used for implementing LRU cache. In case of queue doubly linked list need to implement for proper designing of LRU cache. And in case of hash page number and address of corresponding queue node can be maintained as key and value for helping of maintaining LRU cache scheme.

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