9 Coding Interview Questions to Know

Dec 27, 2021

9 Min Read

One of the scariest software development interview process components is technical code questions. Though the questions may range from company to company, most interviewers are subjected to some variation.

Coding interview questions aren’t supposed to be terrifying. Whether it’s basic coding proficiency, systems expertise, familiarity with design concepts, or just the capacity to communicate with others — including the interviewer – each question interviewers ask to measure something particular about prospects.

Built-in enlisted the help of three people who are acquainted with the software engineering hiring process to discuss nine frequent coding interview questions and the skill sets they are looking for. Questions were taken from famous coding interview practice websites like LeetCode and coding interview prep courses.

Companies want candidates who engage with interviewers, ask for clarification, and don’t give up. Interviewers sometimes have differing opinions about coding problems and their effectiveness in testing specific skills. Still, one thing is clear: companies want candidates who engage with interviewers, ask for clarification, and don’t give up. Collaborate with the interviewer and let your expertise and creativity emerge. That’s most likely what they’re searching for in a candidate.

1. Return A Sorted List By Merging Two Sorted Linked Lists: By Tech Elevator’s Curriculum And Training Director, Josh Tucholski

What is the skill set being tested? You’re not always facing a particular difficulty with a linked list. But you’re running into issues like this one, where the developer has to gather data from two different APIs and display it in an ordered manner. They might be tackling the same issue without using a linked list. “All right, we have two sorted lists of numbers,” we might say to generalize the problem. “How would we go about making a third one that includes them all?”

Is this a fair question for an interview? I’ve yet to come across a linked list in my professional development experience, but the methodology is what matters here. For example, could you discover a method to combine two sorted items into a new sorted order if I handed you two sorted things?

Some firms that aren’t as acquainted with alternate software development education alternatives or more fundamentally founded in tackling profound algorithmic challenges could benefit from queries like these. Unfortunately, we don’t get a lot of questions like these in the areas where Tech Elevator operates in the Midwest. For example, one out of 40 or 50 students may have been given a question with a linked list.

2. Convert A Roman Numeral To An Integer If You’re Given One: By Galvanize Technical Mentor, Cody Daig

What is the skill set being tested? It might be straightforward to figure out once you see the answer; yet, getting to that solution is typically a problem for most individuals because you must consider your current location and the following value in that Roman number. As an example, the number four is “IV.” So you can’t simply say, “‘I,’ that’s one,’ V,’ that’s five — boom, we’ve reached six!” You’re really on number four. So, how can you determine the difference between adding and subtracting while considering not just where you are now but also where you want to go? As a result, it’s got those two distinct elements in it.

Is this a fair question for an interview? It all relies on the interviewee’s prior knowledge when asked this question. Most individuals are probably acquainted with Roman numerals, which is false since not everyone knows or understands Roman numerals. It’s difficult if you don’t even know Roman numerals when you start. In general, I don’t think you’re at all at a disadvantage if you’re open and honest about it, like, “Hey, I’ve never worked with Roman numerals before.”

3. Except For One, Every Element Appears Twice In A Set Of Integers. Go and Find It: By Chainalysis Engineering Director, Anil Kadimisetty

What is the skill set being tested? Not every interviewee who is chosen can address a problem. That doesn’t matter all that much. Because, in the real world, no one person has solutions to all of the issues they’re attempting to tackle. You will only be successful if you cooperate with others, receive input from others, and act on it. What do you do when you’re stuck? Are you able to react well to a clue if it is given to you? That implies you’ll probably be a natural collaborator when you get here.

Is this a fair question for an interview? We’re all about cryptocurrencies at Chainalysis. If we asked about it in an interview — since that’s what we do daily — most people would be stumped because no one truly understands cryptocurrency.

So you question in the most generic manner possible about those things while avoiding addressing the domain-specific concerns. If you strip away the domain knowledge, you’ll end up in a similar situation. So that’s the situation. It raises the recruiting hurdle for all applicants, regardless of their domain expertise. It is an excellent equalizer.

4. Print The Bottom View From Left To Right From A Binary Tree: By Josh Tucholski at Tech Elevator

What is the skill set being tested? When it comes to database structure and design, many people will mention trees — it’s not about tables and keys but rather about underlying indexes and how they’re maintained. You’re approaching the area of a database administrator or a database developer who specializes in database fine-tuning.

If a student came into this issue, I would advise them to work with the interviewer rather than abandon. They may want to get down to the level of how they would code this issue. For example, they could discuss classes they might employ, or other data sets dealt with to show how they might address the challenge.

Is this a fair question for an interview? Someone starting in a junior job frequently lacks the professional experience that allows them to stand out and say, “This is what I’m capable of.” As a result, we often use these questions to indicate that applicants have a basic understanding? Unfortunately, these questions presuppose that you have a basic knowledge of computer science.

There are several methods for determining this. Have them talk about a project they worked on mainly, or give them some code and ask them to explain it to you since this will test their ability to communicate what code is doing. Do they skip over a few items while walking through the code? Or do they get rather specific?

5. Examine Whether The Pairs And Order Of “”,””,”(“,”)”,”[“,”]” Are Correct in The Expression Given An Expression String X. The Function Should Return “True” For “[()][()()]()” And “False” For “[(])”, For Example: By Cody Daig at Galvanize

What is the skill set being tested? The stack is the only tool you have to handle this issue. I’d think it’s a relatively simple question once you recognize you should be utilizing a stack. The point is learning to believe in that way, employing a different data structure than you may assume to solve the problem.

You add an open parenthesis, square bracket, or curly brace to the stack when you see them. After that, you must pop from the stack when you observe a closing side of the pair. And if the ending matches the beginning, that’s great. If it doesn’t, it’s either wrong or invalid.

Is this a fair question for an interview? It’s one of my all-time favorite issues. Thinking about it from the viewpoint of data structures, I believe it’s an advantageous ability — even if you’re not building algorithms to check whether parentheses are balanced. But it’s the application of knowledge to tackle the critical issue here. Recognizing that data structures can help you solve this issue quickly and that these data structures are often used when creating apps — and ensuring that you’re utilizing the most efficient data structure feasible to do whatever you’re attempting to do.

6. Find The Rightmost Different Bit in The Binary Representation Of Numbers Given Two Numbers M And N: By Anil Kadimisetty At Chainalysis

What is the skill set being tested? It comes in handy while working with low-level systems because you need to know how things are represented in real physical memory while you’re working at a low level. For example, how is your name kept on the disk when you type it? What is the method for storing this in memory? All of this information is stored in the binary representation of the integers. If you understand this, you’ll be able to build the code that saves data in memory in a very appropriate and efficient manner.

Is this a fair question for an interview? A lot of things need low-level information. Let’s pretend you’re developing an iPhone — not an iPhone app — and you’re working at a fundamental level. We can presume you’re excellent at low-level things if you understand how to handle this issue and can have a debate about it. That’s where it comes in handy. So although this isn’t relevant to every organization, it is beneficial to those who perform a lot of low-level work.

7. The Runtime Of The Following Code (Bigo): By Josh Tucholski At Tech Elevator

What is the skill set being tested? “Algorithmic complexity” is another phrase that is often used. “If I’m going to give someone a block of code, can you tell me what the worst-case scenarios are that I need to think about?” Because it is precisely what BigO and algorithmic complexity imply.

That’s a trigger for the interviewee to consider, “What are some worst-case or edge-case scenarios that I need to be aware of?” And that’s essential because, while accounting for just one or two percent of the total amount of inputs, these are the types of things that often cause our systems to crash.

Is this a fair question for an interview? As software engineers, we all have a propensity to leap right into all of the “what ifs” and edge situations that we need to consider when faced with an issue — particularly after we’ve been burned a couple of times. We tend to strive to solve problems and avoid the worst-case outcomes.

It’s easier to communicate in plain English, “What is this code doing and what is the worst-case scenario?” than it is to remember the difference between BigO(n), linear, logarithmic, n2, or exponential time because you’re relying on someone having been exposed to formal education covered that content.

8. Use Object-Oriented Principles To Design A Parking Lot: By Cody Daig at Galvanize

What is the skill set being tested? “Can you think through how to turn something that isn’t an object at first into a series of objects to accomplish what you’re trying to accomplish?” is the question here. It will differ somewhat depending on the language, but it is ultimately a class. It isn’t easy to persuade you to consider and break down lessons.

Sure, you have the parking lot, and you have parking places. However, if we have a programming need for this, we must consider whether or not a space is occupied. That requires the idea of a vehicle class and the vehicle’s ability to occupy a space. There are entrances, and parking lots might have many levels. So the actual question is whether you can break down this issue and evaluate all of the variables that must be addressed while constructing a parking lot.

Is this a fair question for an interview? It’s customary to have a vague question, but it’s also appropriate for the interviewee to ask further questions afterward. “What are you expecting to get out of this?” Are we talking about a Walmart parking lot? “Are we talking about a multi-story parking garage?” You may ask questions to figure out how complicated something needs to be. However, it is a precious element for them to show your thinking process and things you may need to consider.

9. Avoid Getting Into Infinite Loops If You Were Developing A Web Crawler: By Anil Kadimisetty At Chainalysis

What is the skill set being tested? This issue may be approached from two perspectives. Can you develop a system to address a business issue, for example? You’re breaking down a subject into little chunks, such as how to solve problems by following stages and how to design a system with many components, which is how we solve real-world problems.

Is this a fair question for an interview? You’re not likely to ask a question that the applicant is hearing for the first time in this one. We’re looking for something they already know – the solution should be obvious. So we’d want to talk about the many approaches to solving this challenge. What are the most effective methods? Because it will show us how much they’ve learned and how they stay up with what’s going on, and it will show us how they know new things and keep up with what’s going on.


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