Data Structure Interview Questions

Computers have become a driving force behind the expansion and progression of every discipline. With drastic changes in businesses and other fields, the need for handling voluminous data has become imperative. To cater to the need, new fields like Data Analytics and Data Science have become immensely popular. Both the fields have seen many takers from the past few years and universities across the globe have come up with comprehensive courses in these two sub-fields of Computer Science. While applying for a job, students often find it hard to answer Data Structure interview questions but if they are understood properly, they can be tackled easily as they are based on real-life situations. 

Introduction to Data Structure

Before going any further with Data Structure interview questions, it is important to understand what Data Structure is all about. An important component of Computer Science, Data Structure is a way of collecting and organizing data to bring efficiency in processing and performing operations on that data. Data Structures are generally of two types: Linear Data Structures and Non-Linear Data Structures. Both of them deals with rendering the elements of data in terms of some relationship that helps in effective storage and classification of data. For example, if we are making a list of football players which has their name and age, we can write it like “Ronaldo” 35, “Messi” 32. In simple words, a Data Structure is highly programmed to collect and store data in a classified manner so that it can be accessed easily and different operations can be performed on it. Doing so reduces the complexities and helps in time management during the process. Data Structures help in storing large volumes of data in an efficient way. Some of the common Data Structures are:

• Linked List
• Graph
• Tree
• Stack
• Queue

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Best Data Structure Interview Questions

From startups like Uber and Netflix to big companies like Google, Microsoft and Amazon, they all have one thing in common, which is to store, process and use humungous amounts of data. While recruiting Computer Science graduates for coding and related job profiles, the companies often come up with tricky interview questions to test the aptitude of the students. In order to answer the questions efficiently, understanding a question and the intent of the interviewer is crucial. The questions asked are very basic but may appear tough. With a firm understanding of the subject and with some homework in advance, you can ace the interview. Below, we have compiled a list of Data Structure interview questions for your reference.

• Define Data Structure
• What are the types of Data Structures?
• Differentiate between file structure and storage structure?
• Mention the Data Structure used to perform recursion.
• Are you aware of multidimensional array?
• Write the syntax in C to create a node.
• Give your definition for Linked List Data Structure
• Name some of the drawbacks of array implementation of Queue.
• How many nodes are possible in a binary tree of height K?
• What are the properties of B Tree?
• How to actually implement a bucket sort algorithm?
• Which Data Structures are used in RDBMS, Hierarchical Data Model and Network Data?
• How do we find the missing number in a given integer array of 1-100?
• What is the way to eliminate duplicates from a given array in Java?
• How can we reverse a linked list?
• How can we find the sum of two linked lists using Stack?
• What is the easiest way to implement a binary search tree?
• How is a postorder traversal algorithm implemented?
• Can we implement a counting sort algorithm?
• What is the procedure to implement a radix algorithm?

Data Structure Interview Questions for Freshers

• How are the elements of a 2D array are stored in the memory?
• What are the advantages of Linked List over an array?
• If you are using C language to implement the heterogeneous linked list, what pointer type should be used?
• Why do we need to do an algorithm analysis?
• Which data structures are used for BFS and DFS of a graph? 
• Which Data Structure Should be used for implementing LRU cache? 
• Which data structures are applied when dealing with a recursive function?
• What are the advantages of a linked list over an array? In which scenarios do we use Linked List and when Array?
• Are linked lists considered linear or non-linear data structures?
• What is the minimum number of nodes that a binary tree can have?
• Differentiate between file and structure storage structure.
• What operations can be performed on queues?

Data Structure Interview Questions for Java Developers

• How to find the third element from the end in a linked list in one pass?
• How do you find duplicates in an array if there is more than one duplicate?
• What is the difference between Stack and Queue data structure?
• In an integer array, there is 1 to 100 number, out of one is duplicate, how to find?
• How to find if a linked list has a loop?
• How to reverse String in Java?
• Write a Java program to implement Stack in Java?
• How to reverse a linked list using recursion and iteration?
• What is a binary search tree?

Data Structure Interview Questions for Experienced Candidates

• What are the types of searching used in Data Structures?
• How does binary search work?
• How are individual elements accessed in an array?
• What is a queue in Data Structures?
• What is the working of a selection sort
•  What is the meaning of a post-fix expression in Data Structures?
• What are the minimum nodes binary trees can have?
• Pointers allocate memory for data storage. True or False?
• State the difference between Linear and Non-linear Data Structures.
• Which is the fastest sorting algorithm available?
• How do you remove duplicates from an array in place? 
• How do you reverse an array in place in Java? 
• What is a binary tree?
• What is the meaning of stack?

Data Structure Interview Questions Python

• How would you convert a list into a tuple?
• What is the difference between an array and a list?
• How is memory managed in Python?
• How do you achieve multithreading in Python?
• How would you convert a list to an array?
• What is a lambda function? Give an example of when it’s useful and when it’s not.
• What is monkey patching?
• What is pickling and unpickling?
• What advantages do NumPy arrays offer over (nested) Python lists?
• Explain inheritance in Python with an example
• What is polymorphism in Python?
• Explain the difference between range() and xrange()
• Explain the differences between Flask and Django.
• What is PYTHONPATH?

Data Structure interview questions may be followed by a brief written test where you would have to demonstrate your skills in the subject but if you are having a stronghold on the subject and believe in your capabilities it is not that hard to ace the interview. To get expert advice on how to crack interviews and the best career guidance to help you propel yourself towards a successful career in the field, reach out to our professional counsellors at Leverage Edu.