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Data Structures for Coding Interviews in Java

The ultimate guide to data structures for coding interviews, developed by FAANG engineers. Practice with interview questions from top companies. Get interview-ready in just a few hours.

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Overview

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Data structures are amongst the fundamentals of Computer Science and an important decision in every program. Consequently, they are also largely categorized as a vital benchmark of computer science knowledge when it comes to industry interviews. This course contains a detailed review of all the common data structures and provides implementation level details in Java to allow readers to become well equipped. Now with more code solutions, lessons, and illustrations than ever, this is the course for you!

Data structures are amongst the fundamentals of Computer Science and an important decision in every program. Consequently, they ...Show More

TAKEAWAY SKILLS

Programming Language

Java

Prepare for Interview

Data Structures

Time Complexity

Content

230 Lessons22 Quizzes65 Challenges

Complexity Measures

22 Lessons

Sharpen your skills in measuring and evaluating time and space complexities of algorithms.

Comparing Algorithms

Example: Measuring Time Complexity of a Single Loop Algorithm

Example: Time Complexity of an Algorithm With Nested Loops

Introduction to Asymptotic Analysis and Big O

Other Common Asymptotic Notations and Why Big O Trumps Them

Useful Formulae

Common Complexity Scenarios

Challenge: Big (O) of Nested Loop with Addition

Solution: Big O of a Nested Loop with Addition

Challenge: Big (O) of Nested Loop with Subtraction

Solution: Big O of a Nested Loop with Subtraction

Challenge: Big O of Nested Loop with Multiplication

Solution: Big O of Nested Loop with Multiplication

Challenge: Nested Loop with Multiplication (Basic)

Solution: Nested Loop with Multiplication (Basic)

Challenge: Nested Loop with Multiplication (Intermediate)

Solution: Nested Loop with Multiplication (Intermediate)

Challenge: Nested Loop with Multiplication (Advanced)

Solution: Nested Loop with Multiplication (Advanced)

Challenge: Nested Loop with Multiplication (Pro)

Solution: Nested Loop with Multiplication (Pro)

Complexity Interview Questions

Arrays

26 Lessons

Get started with arrays, lists essentials, and solving various array manipulation challenges.

What is an Array?

Two Dimensional Arrays

What Is a List?

Challenge: Remove Even Integers From Array

Solution: Remove Even Integers From Array

Challenge: Merge Two Sorted Arrays

Solution: Merge Two Sorted Arrays

Challenge: Find Two Numbers That Add Up to K

Solution: Find Two Numbers That Add Up to K

Challenge: Product of Array Except Self

Solution: Product of Array Except Self

Challenge: Find Minimum Value in Array

Solution: Find Minimum Value in Array

Challenge: First Non-Repeating Integer in an Array

Solution: First Non-Repeating Integer in an Array

Challenge: Find Second Maximum Value in an Array

Solution: Find Second Maximum Value in an Array

Challenge: Rotate Array

Solution: Rotate Array

Challenge: Rearrange Positive & Negative Values

Solution: Rearrange Positive & Negative Values

Challenge: Rearrange Sorted Array in Max/Min Form

Solution: Rearrange Sorted Array in Max/Min Form

Challenge: Maximum Subarray

Solution: Maximum Subarray

Array Interview Questions

Linked Lists

31 Lessons

Examine linked list operations, including insertion, deletion, traversal, and efficiency comparisons.

Stack/Queues

25 Lessons

Grasp the fundamentals of stacks and queues, their implementations, and common challenges.

Graphs

25 Lessons

Dig into the concepts, representation, and operations of various graph types and traversal algorithms.

Trees

38 Lessons

Investigate tree types, structures, operations, and problems for efficient coding with trees.

Trie (Advanced Trees)

14 Lessons

Master the steps to construct and utilize Tries for efficient string storage and retrieval.

Heaps

14 Lessons

Step through the concepts and applications of heaps, their operations, and transformations.

Hash Tables

33 Lessons

Grasp the essentials and practical implementations of hash tables, tackling collisions, and solving challenges using hashing in Java.

10.

Summary of Data Structures

2 Lessons

Go hands-on with linear and non-linear data structures for coding efficiencies.

Certificate of Completion

Showcase your accomplishment by sharing your certificate of completion.

Course Author:

Coderust

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Developed by MAANG Engineers

Every Educative lesson is designed by a team of ex-MAANG software engineers and PhD computer science educators, and developed in consultation with developers and data scientists working at Meta, Google, and more. Our mission is to get you hands-on with the necessary skills to stay ahead in a constantly changing industry. No video, no fluff. Just interactive, project-based learning with personalized feedback that adapts to your goals and experience.

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Personalized Interview Prep

Skip the LeetCode grind with a custom roadmap that adapts to your goals. Hands-on practice for Coding Interviews, System Design, and more.

Mock Interviews

Test your skills in a simulated interview setting. Receive personalized feedback based on your performance. Available for Coding Interviews, System Design, and more.

AI Prompt

Build prompt engineering skills. Practice implementing AI-informed solutions.

Code Feedback

Evaluate and debug your code with the click of a button. Get real-time feedback on test cases, including time and space complexity of your solutions.

Explain with AI

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AI Code Mentor

AI Code Mentor helps you quickly identify errors in your code, learn from your mistakes, and nudge you in the right direction — just like a 1:1 tutor!

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Free Resources

Frequently Asked Questions

Which data structure should be used in Java?

In Java, the choice of data structure depends on the specific use case:

Array: Use when you need fast access by index and the collection size is fixed.
ArrayList: Use for dynamic arrays when you frequently access elements by index and occasionally add or remove elements.
LinkedList: Use when you need frequent insertions and deletions, especially at the beginning or middle of the list.
HashMap: Use for key-value pairs when you need fast lookups, insertions, and deletions based on keys.
HashSet: Use to store unique elements with no duplicates and when order does not matter.
TreeMap: Use when you need key-value pairs sorted by their keys.
Stack: Use for last in, first out (LIFO) operations.
Queue: Use for first in, first out (FIFO) operations.
PriorityQueue: Use when you need elements sorted or retrieved by priority.

Choose the data structure that best matches your performance requirements for the specific operations you need.

Is Java a good choice for coding interviews?

Yes, Java is an excellent choice for coding interviews. Many companies accept and favor it because of its clear syntax, making code easy to read and understand. Java’s strong typing catches errors at compile-time, which can help ensure your solution is robust and error-free. Additionally, Java offers a rich standard library (java.util), which provides efficient data structures and utility functions to implement common algorithms quickly. Its performance is also reliable, making it suitable for handling time-sensitive problems. Given its popularity and versatility, Java is a solid choice for technical interviews.

How to crack a Java coding interview

To crack a Java coding interview, master core Java concepts like object-oriented programming (OOP), exception handling, collections framework, and multithreading. Practice solving common algorithmic problems using Java’s data structures, such as ArrayList, HashMap, and TreeSet, while understanding their time complexities. Get comfortable writing clean, efficient code and explaining your thought process clearly. Familiarize yourself with Java’s syntax, best practices, and nuances. Review design patterns, JVM internals, and Java-specific features that may be relevant to the role you’re interviewing for. Regularly practice mock interviews to build confidence and improve your problem-solving speed.

Is Java coding difficult?

Java coding is not inherently difficult, but it does have a learning curve, especially for beginners. Its syntax is relatively straightforward and readable, and its object-oriented nature helps organize code efficiently. However, mastering Java involves understanding various concepts like data structures, algorithms, exception handling, concurrency, and knowing its extensive standard library. Java becomes easier with consistent practice and a solid grasp of programming fundamentals. The key is building a strong foundation and practicing to become proficient.

Is Java faster than C++?

Java is generally slower than C++ because Java is an interpreted language that runs on the Java virtual machine (JVM), which adds an extra layer of abstraction and overhead. In contrast, C++ is a compiled language that translates directly into machine code, resulting in faster execution. However, Java’s just-in-time (JIT) compiler optimizes code at runtime, narrowing the performance gap in many cases. Ultimately, C++ is often chosen for performance-critical applications, while Java offers better portability and ease of use.