Coding Interview Crash Course: DSA (+ Cheat Sheet)

In the realm of coding interviews, your success hinges on two vital concepts: Data Structures & Algorithms (DSA).

If you studied computer science in university, you probably covered these key pillars — but if you’re anything like me, there’s a good chance you forgot all about them once you left school. Today, I’ll highlight why a solid foundation in DSA can actually be an overlooked difference-maker in a coding interview setting.

Revisiting and solidifying your understanding of DSA can make a huge difference in your interview performance. Remember, whether you're aiming for a general software engineering role or a niche specialization, Data Structures & Algorithms are the basis of every question you face.

However, DSA is more than just a ticket to acing interviews; it's a foundation that will serve you throughout your career. Having a solid understanding of DSA concepts will help you efficiently break down and tackle real-world problems you'll face every day. 

To assist you on this journey, we've compiled an array of comprehensive courses centered around Algorithms for Coding Interviews (available in Python, Java, and C++). These courses will equip you with the knowledge and hands-on experience necessary to tackle coding interviews with confidence.

Additionally, here are some Data Structures courses that will help you build a solid foundation for coding interviews:

• Data Structures and Algorithms in Python
• Data Structures with Generic Types in Python
• Data Structures in JavaScript: Visualizations & Exercises

First, I’ll explain why Data Structures & Algorithms should be part of every developer’s toolkit. I'll also include a cheat sheet breaking down 7 top Data Structures for coding interviews.

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DSA: More Than Just Coding Interview Prereqs

Data Structures & Algorithms form the bedrock upon which exceptional systems, applications, and solutions are built. Their history is deeply intertwined with the evolution of computer science itself. Today, DSA stands as a cornerstone of computer science education and a critical skill set for software developers of all kinds.

DSA isn’t confined to a specific interview or job role — its principles are present in every aspect of software development.

Data structures – i.e. the fundamental ways we store or represent data – involve things like arrays, linked lists, queues, and hash maps. Sound familiar? 

Algorithms can be a bit more involved. Some important ones to learn (or re-learn) are Recursion, Insertion sort, and Binary Search. (Don’t worry: I’ll include a handy cheat sheet for these terms once we dive further into them).  

You may recall from school that time and space complexity (sometimes referred to as Big O notation) are the measures we use to analyze algorithms. If you are preparing for interviews, I find it highly beneficial to review these concepts, as well. Having a solid understanding will assist you with optimizing algorithms, selecting the right data structures, and writing efficient code. 

The more you delve into these concepts, the more equipped you’ll be to handle real-world scenarios that arise at work. Regardless of your specialization or seniority, it’s important to brush up on the fundamentals. 

Embrace it, learn it, and apply it. Proficiency in DSA enhances your employability in the long run. Companies look to hire individuals who can demonstrate a concrete understanding of these concepts and can use them to efficiently solve problems in an applied setting.

DSA Study Strategies & Examples

After re-familiarizing yourself with the basics, your next step is to start practicing and applying what you've learned. Dive into practice problems that revolve around the key data structures like linked lists, arrays, and trees. Complete exercises like reversing a linked list, finding max and min in an array, or performing an inorder traversal of a binary search tree. 

These foundational exercises will provide you with the solid base needed to tackle more complex questions in the future. 

Be sure to memorize and be able to apply this essential data structures cheat sheet:

1. Array: Versatile and dynamic list
2. Linked List: Efficient insertions and deletions
3. Hash Table: Quick data retrieval
4. Stack: Last in, first out (LIFO)
5. Queue: First in, first out (FIFO)
6. Heap: Priority data handling
7. Binary Search Tree: Optimal for data search operations

Be prepared to provide a detailed solution to any DSA scenario thrown at you. For example, practice how you would respond if your interviewer were to say: 

“Find the middle value in a linked list.” or “Right rotate the array by one index.”

What steps would you begin with? Rehearse your responses out-loud; the more confident, the better. 

Let’s also not forget about how important it is to have an in-depth understanding of Big O notation. We use Big O to talk about how fast or slow certain operations are. It provides a high-level understanding of how an algorithm will perform as the input size becomes arbitrarily large, helping in selecting the most efficient algorithm for a given problem.

Consistent, hands-on practice and a genuine enthusiasm for mastering DSA concepts will ultimately lead to a successful coding interview experience.

Practice Makes Perfect

It’s no secret that preparing for a coding interview with a focus on DSA requires a structured and comprehensive approach. Remember, converting knowledge into skill is the ultimate goal. With diligent study and practice you'll set yourself on a path to ace your technical interviews.

I know that Data Structures & Algorithms are complex concepts that demand a lot of time, especially if you haven't thought about them since school. Keep in mind that our courses are here to help you learn by giving you structured guidance for some of the trickiest aspects of computer science. Plus, all of the hands-on practice will help you solidify your skills and retain these essential concepts for years to come. 

After all, knowing DSA isn’t just about impressing interviewers. It’s about giving yourself the right foundation to efficiently and reliably solve real-world problems.

When you are ready to put your DSA skills to the test, I highly recommend our new coding interview crash course: Educative-99.

Internalize 26 coding interview patterns (based on key data structures and algorithms) and practice the essentials through 99 hand-selected problems. Links here:

• Educative-99 in Python
• Educative-99 in Java
• Educative-99 in C++
• Educative 99 in JavaScript
• Educative 99 in Go

Happy Learning!

Free Webinar: Get Hired in 2024

We’ve seen a lot of changes in the tech hiring market in the past year, including the massive onset of AI and instability in the economy. Let’s talk about how to approach these changes in your job search. 

This virtual event from our partners at Hired is your direct line to career experts and top companies actively hiring tech talent. Network with employers and discover how to align your skills with their vision. Learn how to compete in interviews and negotiate salaries in a competitive market. 

Fahim ul Haq
CEO & Cofounder
educative.io