10+ Coding Interview Questions Every Programmer Must Know

Theoretically mastering a language is one thing, but presenting your knowledge and skills is what makes you stand out. Coding interviews are designed to check your coding and communication skills and to succeed in this round, you must be well-prepared with a set of questions commonly asked in the interviews.

Types of Coding Questions You Might Face at an Interview

There are many questions on the internet, but in this blog, we have compiled a list of 10+ crucial coding interview questions you should not miss if you are determined to ace the interview.

Let’s get started.

1. Algorithm-Based Questions

These questions are designed to check the candidate’s problem-solving ability using algorithms. Some sample questions are:

1. How can we compare two algorithms written for the same problem?
2. What do you understand by best, worst, and average case scenario?
3. What do you understand by Asymptotic Notations?

Some Application-based questions that can be asked:

Imagine ]you’re an adventurer with a knapsack looking over a dragon’s hoard.

Given two integer arrays representing the weights and profits of ‘N’ items, implement a function knapSack that finds a subset of these items that will give us the maximum profit without their cumulative weight exceeding a given number capacity. We may select each item only once,  so when we get to it, we can either skip it or put it in the knapsack.

Use the top-down approach with memoization.

These questions are asked to check a candidate’s problem-solving abilities and quick-thinking skills. We suggest you practice as many application-based questions as possible before appearing for the interview.

2. Data Structures Coding Interview Questions

Data structures are the basic programming concept, so you can expect various questions based on this topic. Here is a variety of the same:

1. Can you tell how linear data structures differ from non-linear data structures?

2. How is a binary search tree implemented?

Application-based questions:

You are given the pointer to the head node of a linked list and an integer to add to the list. Create a new node with the given integer. Insert this node at the linked list’s tail and return the linked list’s head node formed after inserting this new node. The given head pointer may be null, meaning the initial list is empty.

Application-based questions are favoured byinterviewers, so be sure to prepare for them.

3. Questions on Arrays

Arrays are a fundamental concept in coding and also the most frequently asked topic in interviews as they have a wide range of applications in software development. By asking questions on arrays, interviewers want to see how well you understand them and how you can apply them to the most challenging codes.

Here are a few sample questions:

1. How do you find the missing number in a given integer array of 1 to 100?
2. How do you find the largest and smallest number in an unsorted integer array?
3. How are duplicates removed from a given array in Java?

Application-based questions:

1. Find the pair with the given sum in the array.
2. Check whether a subarray with sum 0 exists or not.
3. Find maximum length array having a given sum

To master the topic, learn the array concept from the ground up and data structures and basic programming constructors such as loops, recursion, and fundamental operators.

4. Linked-list Coding Interview Questions

Linkedlists form another important topic on the list of the coding interview questions. Linkedlist, like the array, is a linear data structure that stores elements linearly. Here are some questions related to linkedlist:

1. How do you find a single linked-list’s middle element in one pass?
2. How do you check if a given linked list contains a cycle? How do you find the starting node of the cycle?
3. How do you reverse a linked list?
4. How do you reverse a singly linked list without recursion?
5. How do you find the length of a singly linked list?

These questions require having complete knowledge of linked-list and data structures. So, be prepared before appearing for the interview.

5. String-Based Interview Questions

String-based questions, which are character arrays, are another important topic covered in coding interview questions. If you’re comfortable with arrays, mastering string-based questions will be easy. Here are some questions on the same:

1. How do you print duplicate characters from a string?
2. How do you check if two strings are anagrams of each other?
3. How do you print the first non-repeated character from a string?
4. How do you count the number of vowels and consonants in a given string?

Interviews are incomplete without questions based on strings, so learn this topic by heart. We recommend that you first learn array and then move on to this topic because it is a part of the array, and understanding it will be much easier after you have learned array.

Final Thoughts

We have given you the list of the most important coding interview questions that you should prepare diligently before your interview to succeed in that round.

If you find these topics difficult to learn on your own and are looking for a platform to learn them, then you should check out CodeQuotient’s SuperCoders Program. The program is designed to prepare learners for the industry. It is a 3-month program that covers all the aspects of coding and offers live projects and mentorship to make you an expert coder. What’s even better? They offer placement assistance after the completion of the program.

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