Top 10 Data Structure Interview Questions and Answers in 2023

Are you looking to break into the technology industry?

With the increasing demand for data scientists and software engineers, employers are looking for candidates who are well-versed in the fundamentals. The DADS round is one of the hardest rounds in the interview process and is where most aspiring engineers fail. This blog will discuss the top 10 data structure interview questions and answers you should be prepared to answer. We will also provide you with tips and tricks to help you ace your data structure interview. So, let's get started!

Introduction

Data structures are a crucial part of computer science and are a key factor in the success of any software development project. Having a thorough understanding of basic concepts and how to implement them will help you to answer questions in any interview. As a result, any aspiring software developer must have a solid understanding of data structures and how to use them effectively. . Let's not waste any more time and get right into the most frequently asked data structure questions, which are as follows.

1. What is a data structure, and why is it important? 

Answer: A data structure organises and stores data in a computer to be accessed and manipulated efficiently. Data structures can also represent relationships between data items, making it easier to understand and analyse data. Data structures are used in many different areas, such as,

• Software engineering
• Databases
• Artificial intelligence
• Computer graphics

2. What is the difference between a linked list and an array?

Answer: A linked list is a dynamic data structure, while an array is a static data structure. A linked list consists of nodes containing data and a pointer to the next node, while an array is a collection of elements stored in a contiguous memory block. Linked lists are more flexible than arrays, as they can be easily modified and expanded. For example, adding a new node to a linked list is simple. Adding a new element to an array requires allocating a larger memory block and copying the existing elements to the new block. On the other hand, arrays have better performance when accessing data. 

3. What is the time complexity of searching an element in an array?

Answer: Time complexity is the time it takes for an operation to be completed. The time complexity of searching an element in an array depends on the type of search algorithm used. Generally, searching for an element in an array takes O(n) time, where n is the number of elements in the array. A binary search can be used if the array is sorted, which takes O(log n) time.

4. What is the time complexity of inserting an element into a linked list?

Answer: The time complexity of inserting an element into a linked list depends on the type of insertion being performed. If the insertion is at the beginning of the list, the time complexity is O(1). However, if the insertion is at the end of the list, the time complexity is O(n), where n is the number of elements in the list.

5. What is the time complexity of searching an element in a binary search tree?

Answer: The time complexity of searching an element in a binary search tree is O(log n). This means that the time required to search for an element in a binary search tree is proportional to the logarithm of the number of elements in the tree. This is because binary search trees are organised so the elements can be quickly located by comparing them to the root node. This makes searching in a binary search tree much faster than searching in an unordered list.

6. What is a binary search tree?

Answer: A binary search tree (BST) is a type of data structure that allows for efficient searching and sorting of data. It is a tree structure in which each node has at most two children, and each node is labelled with a key to determining its position in the tree. The left subtree contains nodes with less than the node's key, and the right subtree contains more than the node's key. This structure allows for a fast lookup of data, as the data can be located quickly by traversing the tree from the root node to the desired node. Additionally, the BST can sort data efficiently, as the nodes are arranged in an order that makes sorting easy.

7. What is a hash table?

Answer: A hash table is a data structure used to store key-value pairs. It is an associative array-type data structure that can map keys to values. A hash table uses a hash function to compute an index into an array from which the desired value can be found. Hash tables are used to implement associative arrays, sets, and caches. They are also used in database indexing, graph, and string-matching algorithms. Hash tables are very efficient for finding and retrieving data, as they can be searched constantly. Hash tables are hash maps, hash sets, and dictionaries. They are used in many programming languages, including C++, Java, and Python.

8. What are different operations available in stack data structure?

Answer: The main operations available are, 

• Push
• Pop
• Top
• Empty
• Size

9. What is a hashmap?

Answer: A hashmap is a data structure that uses hash tables. This allows data to be accessed quickly and efficiently with a best-case time complexity of (O(1)).

10. What are primitive data types?

Answer: Primitive data types are simple data types present in almost all programming languages. They symbolise a specific process. 

• Integer 
• Character 
• Floating point 
• Double floating point 
• Zoid 

Conclusion

The commonly asked data structure interview questions and answers in 2023 discussed in this blog will provide a comprehensive overview of a recruiter's assessment process. Check out Skill-Lync to get the technical skills you need. Skill-Lync is an online platform that offers various courses on in-demand skills.

Some of the courses we offer include Core and Advanced Python Programming, Data Structures and Algorithms using Python, PG programs on data analytics and data science, Machine learning fundamentals in depth, artificial intelligence, etc. Check out our other blogs and courses to learn about these concepts and add strong value to your resume!