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**Introduction**

Preparing for the hiring process of big product based companies from Google to Microsoft requires an endless amount of practising of problems. These interviews are deemed to be very hard to crack but hold the dreams of many budding software developers.

Well, this can be intimidating! But the good news is that most of them have a defined structure going on from previous years. So the kind of questions that are posed can be predicted after an analysis of last year trends and patterns.

Attempts at such analysis have shown that product based companies essentially focus on evaluating your skills in Data Structures and Algorithms. Understanding why it is so is necessary before we dive into the list of coding interview questions from this topic. We will look at this in the coming section.

**Why the focus on DSA?**

Let’s look at some of the reasons why Data Structures and Algorithms is a significant area of evaluating candidates in interviews of big product-based companies.

**Optimal usage of time and memory:**Companies like Google and Facebook that have a large number of users spread around the world with even more significant amounts of data require that all of this data be taken care of in the most optimal manner. The ability to do this can only be achieved if a programmer has good skill in Data Structures and Algorithms.

**Assessment of problem-solving skills:**DSA is a topic that effectively tests a candidate’s ability to analyze problems and derive solutions to them spontaneously. Thus, making it an excellent parameter to assess an individual’s problem-solving skills.

**Real-life applications:**The applications of data structures in real life are very evident for anyone familiar with the topic. Knowing how computer science concepts are applied and valuable in our daily lives is something that a lot of recruiters indirectly look for.

**Topic-wise must-do Coding Interview Questions**

Since we now know how important it is to master data structures, let’s look at a roadmap of various topics that you need to master, based on an analysis by Parikh Jain, a founding member and instructor at Coding Ninjas.

So here is a compilation of all the must-do coding interview questions sorted topic-wise for your convenience in one place! Make full use of it!

**Arrays** for Coding Interview Questions

The topic to start with is Arrays. An array is a linear data structure with a predefined size in which elements are stored in contiguous blocks of memory. An array can be one-dimensional or multidimensional. Multidimensional arrays need to be studied separately and find their best application in Matrices.

Below is a list of important coding interview questions from this topic. Click on any question to start practising and understanding right away!

- Arrays

- Multi-Dimensional Arrays

**Strings** for Coding Interview Questions

An array that consists of characters as elements is called a string. What makes it different from a character array is that it ends with a special symbol ‘\0’.

Below are a few important questions from this topic.

- Longest Substring Without Repeating Characters
- Anagram Difference
- Shortest substring with all characters
- Minimum operations to make strings equal
- Other Questions Practice Link

**Recursion & Backtracking** for Coding Interview Questions

Recursion is a technique in programming in which a function is called by itself directly or indirectly. It is used to solve complex problems by breaking them into smaller problems. On the other hand, backtracking is a technique that uses recursion to build an overall solution by incrementally going through smaller levels of the problem until the solution is reached. Given are some questions that you must practice from this topic before going for an interview.

- Print Permutations Of String
- Return Subsets Sum to K
- Sudoku
- Replace ‘O’ with ‘X’
- Reach Destination
- Other Questions Practice link

**Linked Lists** for Coding Interview Questions

Linked List is a dynamic linear data structure that consists of nodes where each node consists of two fields – data and pointer. Each node points towards the next node. The first node is called Head that points to the second node and so on. It is of three types – Singly Linked List, Doubly Linked List and Circular Linked List.

- Merge Two Sorted Linked List
- Detect And Remove Loop
- Reverse List In K Groups
- Intersection Of Two Linked List
- Sum Between Zeros
- Other Questions Practice Link

**Stacks & Queues** for for Coding Interview Questions

The arrangement of data in stacks and queues is as their names suggest. In a stack, a visual representation of its data can be seen as one element on top of the other, working on the First In Last Out (FILO) Principle. In a queue, on the other hand, elements are put one after the other, working on the First In First Out (FIFO) principle.

- Implement Stack Using Linked List
- Next Greater Element
- Implement Queue Using Stack
- LRU Cache Implementation
- Evaluation Of Postfix Expression
- Other Questions Practice Link

**Binary Trees** for Coding Interview Questions

A Binary Tree is a tree in which each node consists of at most two children. Each node consists of three fields – data, a pointer to the left child, and a pointer to the right child. Must-do questions for coding interviews from Binary Tree are given below:

- Binary Tree From Parent Array
- Maximum Sum Path From Root To Leaf
- Print Node At Distance K From Given node
- Maximum Width In Binary Tree
- Time To Burn Tree
- Other Questions Practice Link

**Binary Search Tree** for Coding Interview Questions

A Binary Search Tree is a sorted binary tree in which the left subtree of a node consists of values lesser than the value of that node, and the right subtree consists of those greater. Here are some must-do questions from this topic.

- Delete In BST
- Sorted Linked List To Balanced BST
- Kth Smallest Element In BST
- Binary Tree To BST
- Pair Sum in BST
- Other Questions Practice Link

**Priority Queues & Heaps**

A priority queue is a queue in which every value is associated with a priority. Dequeuing takes place in a manner that the element with a higher priority is dequeued before an element with a lower priority. Heaps are a special type of data structure which are based on complete binary trees. They are of two types – Min heap and Max heap. After an analysis,

- Running Median
- Convert Min Heap To Max Heap
- Kth Largest Element In Unsorted Array
- K Most Frequent Words
- Last Stone Weight
- Other Questions Practice Link

**Graphs** for Coding Interview Questions

A Graph is a non-linear data structure that consists of nodes and edges. A node is a vertex and an edge is a line or curve that connects any two vertices. Some important problems for coding interviews from this topic are given below:

- Is Graph A Tree?
- M Coloring Problem
- Snake And Ladder
- Shortest Path In Unweighted Graph
- Alien Dictionary
- Other Questions Practice Link

**Dynamic Programming** for Coding Interview Questions

Dynamic Programming is an optimisation technique working on recursion in which we divide a complex problem into smaller subproblems. It finds many applications in computer science. Must-do problems from this topic are linked as follows:

- Edit Distance
- Rod Cutting Problem
- Longest Palindromic Substring
- Knapsack
- Palindrome Partitioning
- Other Questions Practice Link

**Other Important for Coding Interview Questions**

Apart from the questions categorised above in the form of topics, we have compiled a list of more coding interview questions that you must practice before appearing for any tech interview.

**Frequently Asked Questions**

**What should I study for a coding interview?**

Before you start practicing coding for an interview, you must be familiar with aspects the particular company’s interview focuses on. For product based companies, you must practice data structures and algorithms while for service based companies, you should focus on your software development skills.

**How do I practice coding for an interview?**

After you have knowledge about what kind of questions you need to solve, you must immediately start working on coding the problems that are known to be the most important ones. CodeStudio is the perfect platform to help you get a guided path on how to do this.

**How do you code a question?**

Before you jump to coding the answer to a question, you must firstly understand the question, secondly make test cases, and thirdly do a dry run. Then you should develop a pseudocode which would make it easier for you to develop the final code.

**How do I start coding?**

The first step to starting coding is to learn a programming language that will be the medium for you to communicate with the computer. Which programming language to choose can be based on your future interests, or if not, you can choose any programming language you want because it is merely a medium.

**How do beginners practice coding?**

Beginners should develop a solid foundation by learning one programming language to start and then moving to solve problems in that language to build their problem-solving skills.

**How many hours a day should you practice coding?**

The number of hours required varies from person to person. The important thing is to devote more hours to get stronger in a weak topic and less in reviewing mastered topics. Consistency is key.

**How can I practice coding every day?**

You can practice coding every day by keeping a fixed number of questions to solve every day. Another way can be to set the number of hours.

**Where can I practice coding questions?**

There are various platforms that give you a pool of problems to solve, like CodeChef, Hackerrank, CodeStudio, and LeetCode.

**Key Takeaways**

In this article, we started with a discussion on how being familiar with certain types of questions gives you a boost to qualify for a job at big product-based companies. Then we shed light on why and how data structures and algorithms are the most important topics to master to help you get through any tech interview in product-based companies. Finally, we presented our whole list of questions from all topics of data structures that any candidate aspiring to crack the interviews of big product based companies must master.

**By Khushi Sharma**

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