If you are looking for opportunities in the software engineering field then you need to be well versed with coding interviews. In coding interviews, you are tested on the basis of logical and analytical skills, ability to solve complex problems, your grasp on various concepts like data structures, algorithms, and systems design. The difficulty of a coding interview may vary from company to company, ranging from easy to difficult level. In this article, we will discuss some of the reasons why you can fail a coding interview. We will also discuss how to avoid the mentioned reasons for failure.

Reasons Why You Can Fail A Coding Interview

Having good preparation for a coding interview might seem easy at first sight but the actual scenario can be different. You may knowingly or unknowingly commit mistakes. There are various reasons due to which you can fail a coding interview even after knowing how to code properly in different languages. 

Here are the 10 reasons why you might end up failing a coding interview:

• Not knowing the basics: Understanding the basics is of utmost importance. You may become a good programmer and may even answer tough questions by just looking once at the problem. But, this is not enough. If you do not have enough knowledge as to how different data structures are implemented, how they are stored in memory, how they are retrieved from memory, how the entire process of compilation and execution takes place, you might face problems in a coding interview. This is the reason why you must be well versed in the basics of programming. 
• Using inappropriate data structures: There might be a case where you fail a coding interview on the basis of inappropriate use of data structures. The coding questions might seem easy and confined. However, if the interviewer correlates the problem to a broader picture where you will be working on complex systems then your solution might not work. Consider an example of you choosing 2-3 data structures to achieve different tasks in your code. But if this could be done with the help of a single data structure that can fulfill the requirements of the above three then it is considerably more efficient.
• Using inappropriate algorithms: There might be a case where you fail a coding interview on the basis of inappropriate use of algorithms. Computer Science contains an ocean of algorithms. What to choose and what not to choose is a tough job. You must have a clear understanding of the requirements in the problem and you should pick the algorithm accordingly. Consider an instance when you think says that you must go with a dynamic programming approach but you might end up having a more efficient solution choosing the greedy way. Hence, it is very important for you to go ahead with an appropriate and efficient algorithm.
• Failing due to time constraints: The biggest factor that comes into play when designing an algorithm is the amount of time it takes to execute. If your algorithm is too slow and does unnecessary work then it is of no use. In order to keep yourself aligned with the time complexity, you must be well aware of the constraints mentioned in the problem. After that, you must think in the direction to bring it under a specific time so that it can be executed optimally on any machine.
• Failing due to space constraints: Another factor other than the time complexity is the space complexity. You must be well aware of the space your data structures will take in order to perform the desired task. Your algorithm must match the space requirements in order to be efficient.
• Not starting with a Brute-Force approach: Always start your discussion with a naive approach. An approach that comes to your mind at the first sight without considering any constraint. This approach is something that guarantees you to come up with all possible candidates for the solution without using heuristics. Even if it may lead to high complexity, that’s not an issue. It shows that you start with the ground approach and can gradually optimize further.
• A limited number of approaches: You might even fail if you have only one approach for solving a problem in your mind. After you are done with the brute force approach, you must gradually optimize your solution and come up with different approaches. You must start using heuristics in order to eliminate unnecessary candidates that are part of the solution. Your different approaches show that you have a wide range of thoughts and different ideas as to how to approach a particular problem to solve it.
• Rushing for the discussion: After the interviewer asks you a coding question you must always take your time. Even if you know the solution or you have seen that problem somewhere else, you must not directly jump to the solution. Wait for a while, observe the constraints carefully, and write on pen and paper first. Hurrying might end you up speaking something which is wrong or may lead to an error in front of the interviewer. So always stay calm and take your time before discussing your solution.
• No dry run of the code: When you are done with writing the code you must also dry run on the sample test cases and even your own test cases. By doing this you will be 100% sure of the control flow that will yield the correct output. Always keep pen and paper handy so that you can perform a dry run on various test cases.
• Dirty Code: At last, your code must be neat and clean. You must always use proper naming conventions for the variables and functions. For example: if you need to check if a number is prime or not, you must create a separate function to do so. Also, naming must be accurate. In this case, you may name the function as isPrime(number N), which clearly tells the interviewer what you want to do. You must avoid using random names like fun(), myfunction(), etc. as they might result in a negative impact on your interview. Also, try to include comments in your code thoroughly for easier understanding. A neat and clean code adds a strong hire factor to your performance.

Conclusion

In this article, we have discussed some common reasons due to which you can fail a coding interview. If these mistakes are corrected early in your preparation it will turn out to be fruitful in your upcoming interviews. Keep all these factors in your mind and prepare thoroughly. You can learn python, java, and other programming languages to answer the basic questions regarding the properties of programming languages. For the advanced questions, you should prepare accordingly.

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