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Top Java Data Structures Interview Questions and Answers to Practice

by Interview Kickstart Team in Interview Questions
October 10, 2024
Crack Java coding interview questions with FAANG experts!

Top Java Data Structures Interview Questions and Answers to Practice

Last updated by Vartika Rai on Sep 25, 2024 at 10:44 PM | Reading time: 10 minutes

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Technical interviews at FAANG+ companies fundamentally test your ability to solve complex data structures and algorithms problems. Interview questions about Java Data Structures are frequently asked during coding rounds of technical interviews. The best way to ace tough technical interviews is to sharpen your problem-solving skills by identifying and classifying problems based on inherent patterns.

Preparing thoroughly for Java data structures interview questions by devoting adequate time to honing your problem-solving skills is essential for standing out from the crowd. If you have a technical interview coming up, it is highly recommended that you answer at least 1-2 Java data structures interview questions per day.

In this article, we’ll look at some Java data structures interview questions asked at FAANG+ interviews. These questions will give you an idea of what to expect at these interviews and devise a sound strategy that will help you get through challenging technical rounds.

If you’re a software engineer, coding engineer, software developer, engineering manager, or tech lead preparing for tech interviews, check out our technical interview checklist, interview questions page, and salary negotiation e-book to get interview-ready!

Having trained over 9,000 software engineers, we know what it takes to crack the most challenging tech interviews. Since 2014, Interview Kickstart alums have landed lucrative offers from FAANG and Tier-1 tech companies, with an average salary hike of 49%. The highest-ever offer received by an IK alum is a whopping $933,000!

At IK, you get the unique opportunity to learn from expert instructors who are hiring managers and tech leads at Google, Facebook, Apple, and other top Silicon Valley tech companies.  Our reviews will tell you how we’ve shaped the careers of thousands of professionals aspiring to take their careers to new heights.

Want to nail your next tech interview? Sign up for our FREE Webinar.

Let’s look at some common Java data structures interview questions asked in technical interviews. Here’s what we’ll cover:

  • Java Data Structures Interview Questions on Arrays
  • Java Data Structures Interview Questions on Linked Lists
  • Java Data Structures Interview Questions on Strings
  • Java Data Structures Interview Questions on Trees and Graphs
  • FAQs on Java Data Structures Interview Questions

Before moving on to Java data structures interview questions, let’s look at some essential data structures and algorithms topics that regularly feature technical interviews at FAANG+ companies.

Java Data Structures Interview Questions on Arrays

  1. For a given unsorted array, write a program to find a contiguous subarray that adds to a given number in the array
  2. For two unsorted arrays where elements are in non-decreasing order, write a code to merge the two arrays such that the new array is sorted
  3. For a given array of size N-1, containing integers in the range from 1 to N, write a program to find the missing element in the array
  4. For a given array containing positive integers, write a code to return the sum of the elements of the array
  5. For a given unsorted array of size N, write a code to rotate it anticlockwise, by D elements
  6. For a given array of size N, write a code to print the reverse of the array
  7. For a given array A, write a code to delete the duplicate elements in the array
  8. For a given array Arr[] containing integer elements, write a code to find the minimum and maximum elements of the array
  9. For a given array of size N containing distinct integer numbers, write a code to sort the array in the wave fashion
  10. From a given array containing integer values, write a code to find the maximum subarray of non-negative numbers

Take a look at the Concept of Arrays in Java Data Structures here.

Java Data Structures Interview Questions on Strings

  1. For a given String S, write a code to reverse the string without disturbing the individual words
  2. For a given String, write a program to print all permutations (of its characters) and return it in a lexicographically sorted fashion
  3. Write a program function for a given String S to find the longest palindromic substring. A palindromic string reads the same even backward
  4. For a given String that has its elements represented in Roman Values, write a code to convert the String into integer values
  5. For a given String S, write a program to remove duplicate elements from the String
  6. For a given String S, write a code to find the minimum number of elements or characters that need to be inserted to convert it into a palindrome
  7. For a given String S, write a program to find the length of the longest Substring with distinct values
  8. For a given String S, write a code to remove successive duplicate characters recursively
  9. For two strings, A and B, write a program to figure out if B can be obtained by rotating A in at least two places
  10. Write a program to implement the strstr function

Java Data Structures Interview Questions on Linked Lists

  1. How do you insert a node at the end of a Linked List?
  2. How do you delete a particular node in a Linked List?
  3. Write a code to reverse a Singly Linked List.
  4. Write a code to add two numbers represented by Linked Lists
  5. Write a function to remove the nth node from a Linked List
  6. Write a program to swap adjacent nodes in a Linked List
  7. Write a code to reverse a Linked List from position X to position Y
  8. For a given Linked List, write a code to return the node value where the cycle in question begins
  9. Write a program to flatten a given multi-level linked list
  10. Write a code to find the next greater node for a given Linked List
  11. Write a code to clone a given Linked List with the next random pointer

Java Data Structures Interview Questions on Trees and Graphs

  1. For a given binary tree where each node contains a number, find the maximum path sum from one node to the other
  2. For a given binary tree B, write a function to calculate its height
  3. For a given binary tree that contains all unique values, write a code to find the lowest common ancestors of the nodes
  4. For a given binary tree, write a function to connect nodes that are at the same level
  5. For a given binary tree T, write a function to find its spiral order traversal
  6. For a given binary tree, write a program that traces its vertical traversal
  7. For a given binary tree T, write a code to print the bottom view of the tree from left to right
  8. You're given the root of a binary tree T. Write a program to find out of it is a Binary Search Tree or not
  9. For a given Directed Graph with V vertices and E edges, write a program that identifies that number of strongly connected components in the graph
  10. For a given Directed Acyclic Graph, write a program that finds the topological sorting in the graph
  11. For a given graph with E edges and V vertices, find out whether the graph contains a cycle or not
  12. For a given directed graph, perform Breadth-First Search
  13. For a given undirected, connected graph, perform Depth First Search
  14. Write a code to convert a given binary Tree into a Doubly Linked List
  15. For two binary trees that are given, write a program to find out if they’re identical or not

Learn about AVL in Data Structures and Algorithms here.

These Java data structures interview questions will help you thoroughly prepare for your upcoming technical interview. For more problems with optimal solutions, visit our Problems Page.

FAQs on Java Data Structures Interview Questions

Q1. What topics should you prepare to solve Java data structures interview questions in a technical interview?

To solve Java data structures interview questions, you must be thorough with the following concepts - arrays, strings, linked lists, recursion, hash tables, graphs, trees, and dynamic programming.

Q2. When can you expect Java data structures interview questions in technical interviews?

You can expect Java data structures interview questions during the Technical Phone Screen Round and the On-site interview round.

Q3. Which is the best way to improve your problem-solving skills to solve Java data structures interview questions effectively?

The best way to improve your problem-solving skills is to identify patterns in the problems you solve and classify problems based on similar patterns. That way, you can apply existing patterns to solve new problems and tackle tricky and challenging problems at the interview.

Q4. Are Java data structures interview questions asked in systems design interviews?

No, Java data structures interview questions are asked only in coding interviews of companies and not in systems design interviews.

Q5. Should you be adept with data structures and algorithms if you give interviews for ML or Security Engineering positions?

Yes, testing your knowledge in data structures and algorithms is a fundamental interview assessment exercise that FAANG+ companies adopt. Thus, even if you’re applying to ML or Security Engineering positions, you can expect a few DSA problems at your interview.

Get Ready for Your Upcoming Technical Interview

If you’ve begun preparing for your next technical interview, register for Interview Kickstart’s technical interview webinar and get ahead by understanding foolproof and advanced strategies from industry experts.  These reviews from our alums will tell you exactly how we’ve helped thousands of students to scallop their professional careers by helping them crack technical interviews at the biggest companies.

Sign Up Now to Uplevel Your Career!





Author
Vartika Rai
Product Manager at Interview Kickstart | Ex-Microsoft | IIIT Hyderabad | ML/Data Science Enthusiast. Working with industry experts to help working professionals successfully prepare and ace interviews at FAANG+ and top tech companies
The fast well prepared banner

Technical interviews at FAANG+ companies fundamentally test your ability to solve complex data structures and algorithms problems. Interview questions about Java Data Structures are frequently asked during coding rounds of technical interviews. The best way to ace tough technical interviews is to sharpen your problem-solving skills by identifying and classifying problems based on inherent patterns.

Preparing thoroughly for Java data structures interview questions by devoting adequate time to honing your problem-solving skills is essential for standing out from the crowd. If you have a technical interview coming up, it is highly recommended that you answer at least 1-2 Java data structures interview questions per day.

In this article, we’ll look at some Java data structures interview questions asked at FAANG+ interviews. These questions will give you an idea of what to expect at these interviews and devise a sound strategy that will help you get through challenging technical rounds.

If you’re a software engineer, coding engineer, software developer, engineering manager, or tech lead preparing for tech interviews, check out our technical interview checklist, interview questions page, and salary negotiation e-book to get interview-ready!

Having trained over 9,000 software engineers, we know what it takes to crack the most challenging tech interviews. Since 2014, Interview Kickstart alums have landed lucrative offers from FAANG and Tier-1 tech companies, with an average salary hike of 49%. The highest-ever offer received by an IK alum is a whopping $933,000!

At IK, you get the unique opportunity to learn from expert instructors who are hiring managers and tech leads at Google, Facebook, Apple, and other top Silicon Valley tech companies.  Our reviews will tell you how we’ve shaped the careers of thousands of professionals aspiring to take their careers to new heights.

Want to nail your next tech interview? Sign up for our FREE Webinar.

Let’s look at some common Java data structures interview questions asked in technical interviews. Here’s what we’ll cover:

  • Java Data Structures Interview Questions on Arrays
  • Java Data Structures Interview Questions on Linked Lists
  • Java Data Structures Interview Questions on Strings
  • Java Data Structures Interview Questions on Trees and Graphs
  • FAQs on Java Data Structures Interview Questions

Before moving on to Java data structures interview questions, let’s look at some essential data structures and algorithms topics that regularly feature technical interviews at FAANG+ companies.

Java Data Structures Interview Questions on Arrays

  1. For a given unsorted array, write a program to find a contiguous subarray that adds to a given number in the array
  2. For two unsorted arrays where elements are in non-decreasing order, write a code to merge the two arrays such that the new array is sorted
  3. For a given array of size N-1, containing integers in the range from 1 to N, write a program to find the missing element in the array
  4. For a given array containing positive integers, write a code to return the sum of the elements of the array
  5. For a given unsorted array of size N, write a code to rotate it anticlockwise, by D elements
  6. For a given array of size N, write a code to print the reverse of the array
  7. For a given array A, write a code to delete the duplicate elements in the array
  8. For a given array Arr[] containing integer elements, write a code to find the minimum and maximum elements of the array
  9. For a given array of size N containing distinct integer numbers, write a code to sort the array in the wave fashion
  10. From a given array containing integer values, write a code to find the maximum subarray of non-negative numbers

Take a look at the Concept of Arrays in Java Data Structures here.

Java Data Structures Interview Questions on Strings

  1. For a given String S, write a code to reverse the string without disturbing the individual words
  2. For a given String, write a program to print all permutations (of its characters) and return it in a lexicographically sorted fashion
  3. Write a program function for a given String S to find the longest palindromic substring. A palindromic string reads the same even backward
  4. For a given String that has its elements represented in Roman Values, write a code to convert the String into integer values
  5. For a given String S, write a program to remove duplicate elements from the String
  6. For a given String S, write a code to find the minimum number of elements or characters that need to be inserted to convert it into a palindrome
  7. For a given String S, write a program to find the length of the longest Substring with distinct values
  8. For a given String S, write a code to remove successive duplicate characters recursively
  9. For two strings, A and B, write a program to figure out if B can be obtained by rotating A in at least two places
  10. Write a program to implement the strstr function

Java Data Structures Interview Questions on Linked Lists

  1. How do you insert a node at the end of a Linked List?
  2. How do you delete a particular node in a Linked List?
  3. Write a code to reverse a Singly Linked List.
  4. Write a code to add two numbers represented by Linked Lists
  5. Write a function to remove the nth node from a Linked List
  6. Write a program to swap adjacent nodes in a Linked List
  7. Write a code to reverse a Linked List from position X to position Y
  8. For a given Linked List, write a code to return the node value where the cycle in question begins
  9. Write a program to flatten a given multi-level linked list
  10. Write a code to find the next greater node for a given Linked List
  11. Write a code to clone a given Linked List with the next random pointer

Java Data Structures Interview Questions on Trees and Graphs

  1. For a given binary tree where each node contains a number, find the maximum path sum from one node to the other
  2. For a given binary tree B, write a function to calculate its height
  3. For a given binary tree that contains all unique values, write a code to find the lowest common ancestors of the nodes
  4. For a given binary tree, write a function to connect nodes that are at the same level
  5. For a given binary tree T, write a function to find its spiral order traversal
  6. For a given binary tree, write a program that traces its vertical traversal
  7. For a given binary tree T, write a code to print the bottom view of the tree from left to right
  8. You're given the root of a binary tree T. Write a program to find out of it is a Binary Search Tree or not
  9. For a given Directed Graph with V vertices and E edges, write a program that identifies that number of strongly connected components in the graph
  10. For a given Directed Acyclic Graph, write a program that finds the topological sorting in the graph
  11. For a given graph with E edges and V vertices, find out whether the graph contains a cycle or not
  12. For a given directed graph, perform Breadth-First Search
  13. For a given undirected, connected graph, perform Depth First Search
  14. Write a code to convert a given binary Tree into a Doubly Linked List
  15. For two binary trees that are given, write a program to find out if they’re identical or not

Learn about AVL in Data Structures and Algorithms here.

These Java data structures interview questions will help you thoroughly prepare for your upcoming technical interview. For more problems with optimal solutions, visit our Problems Page.

FAQs on Java Data Structures Interview Questions

Q1. What topics should you prepare to solve Java data structures interview questions in a technical interview?

To solve Java data structures interview questions, you must be thorough with the following concepts - arrays, strings, linked lists, recursion, hash tables, graphs, trees, and dynamic programming.

Q2. When can you expect Java data structures interview questions in technical interviews?

You can expect Java data structures interview questions during the Technical Phone Screen Round and the On-site interview round.

Q3. Which is the best way to improve your problem-solving skills to solve Java data structures interview questions effectively?

The best way to improve your problem-solving skills is to identify patterns in the problems you solve and classify problems based on similar patterns. That way, you can apply existing patterns to solve new problems and tackle tricky and challenging problems at the interview.

Q4. Are Java data structures interview questions asked in systems design interviews?

No, Java data structures interview questions are asked only in coding interviews of companies and not in systems design interviews.

Q5. Should you be adept with data structures and algorithms if you give interviews for ML or Security Engineering positions?

Yes, testing your knowledge in data structures and algorithms is a fundamental interview assessment exercise that FAANG+ companies adopt. Thus, even if you’re applying to ML or Security Engineering positions, you can expect a few DSA problems at your interview.

Get Ready for Your Upcoming Technical Interview

If you’ve begun preparing for your next technical interview, register for Interview Kickstart’s technical interview webinar and get ahead by understanding foolproof and advanced strategies from industry experts.  These reviews from our alums will tell you exactly how we’ve helped thousands of students to scallop their professional careers by helping them crack technical interviews at the biggest companies.

Sign Up Now to Uplevel Your Career!





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