Preparing for technical interviews requires a good mix of problem-solving, design, and coding skills. Companies hiring for tech roles typically have a technical round that tests a candidate’s knowledge on programming, coding, data structures, algorithms, and systems design. If you’re a programmer, with 10+ years of employment experience, you’ll find questions asked in these interviews starkly deviate from your everyday programming tasks.
The most popular technology companies like Apple, Amazon, Netflix, Google, and Facebook, have a comprehensive testing approach designed to identify an applicant’s key strengths in various technical areas.
Here are some of the most common technical questions asked in interviews conducted by these companies, over the years. Questions are categorized under Data Structures, Systems Design and Algorithmic Coding - the three main topics on which questions are commonly asked.
Technical interview questions on data structures
1. Mention the major data structures used in the following areas:
a. Network Data Model
b. Hierarchical Data Model
c. Relational Database Management System
Ans - a. Network Data Model: Graph
b. Hierarchical data Model: Trees
c. RDBMS: Arrays.
2. What is the minimum number of queues required to implement a priority queue?
Ans - The minimum number of queues required is two. One queue for storing data, and the second queue for priorities.
3. Which data structure is used for recursion?
Ans - The data structure used to achieve recursion is Stack. Owing to its Last In First Out (LIFO) attribute, it recollects its caller and returns appropriately when the function has to perform a return. Note that recursive functions, individually, have iterative or non-recursive functions.When iterative functions are employed, an explicit stack is actively used.
4. What are the various methods available to store sequential files?
Ans - There are 4 methods available:
a. Natural Merging
b. Polyphase Sort
c. Straight Merging and
d. Distribution of Initial Runs
5. Convert the following expression into Prefix and Postfix notations:
((A+B))xC – (D-E)^(F+G))
Ans - a. Prefix Notation: -*+ABC^ - DE + FG
b. Postfix Notation: AB+ C*DE- FG + ^-
6. What is the minimum number of nodes that a certain binary tree can possess?
Ans - A binary tree can have a minimum of “0” nodes. This usually occurs when the nodes in question have NULL values.
7. What is a graph?
Ans - A graph is a common type of data structure that contains within itself a set of ordered pairs. These ordered pairs, commonly referred to as arcs or edges, are primarily used to connect nodes. Nodes are places where data can be stored or retrieved.
8. Which data structures are employed in the DFS and BFS of a graph?
Ans - Stack is used for the DFS of a graph and Queues are used for the BFS of a graph.
9. How do you implement a stack using a queue?
Ans - A stack can, typically, be implemented by employing two queues. If the stack to be implemented is represented as ‘S’ and the two queues are represented as ‘Q1’ and ‘Q2’, then the stack ‘S’ can be implemented in the following two ways:
1. By making the enqueue operation costly: Under this method, the oldest element entered is always on top to ensure the dequeue operation becomes easy as it pops from the top of the stack.
2. By making the dequeue operation costly: Under this method, the most recent element is entered on top of Stack 1.n the dequeue operation, if Stack 2 is found to be empty, all the elements are shifted to Stack 2 and the entire stack is returned.
Additional interview questions on data structures:
10. Explain the features of an AVL Tree.
11. What are the various types of collision resolution techniques?
12. Explain the functioning of a recursive algorithm.
13. Describe the method used in performing a Fibonacci search.
14. Explain how each sorting technique works and the applications of various sorting techniques.
Systems design technical interview questions
1. How do you design a Web Crawler?
Ans - A crawler is a program which scans websites for information. The information becomes useful in creating entries for search engine indexes. While designing web crawlers, it is essential to note that dynamic web pages need to be prioritized and monitored more often than static pages.
2. What is endpoint protection?
Ans - Endpoint protection is a feature in a database which allows you to prevent certain operations from occurring in your system when a set of tasks is complete. Endpoint protection typically protects a system from overloading by reducing its task-burden through prioritizing and monitoring.
3. What are the essential aspects to keep in mind while designing the autocomplete functionality?
a. Provide a typeahead suggestion
b. Ensure your framework supports personalization
c. Calculate the amount of space required for your data
d. Note the queries per second (QPS) that are handled by your system for better tracking and prioritizing.
4. Explain the difference between relational and non-relational databases.
a. Relational databases have a pre-set relationship between data stored in the system. Data in relational databases is typically represented in rows and columns. Most relational databases support a querying language such as MySQL.
b. Non-relational databases have a more flexible structure and the data is typically represented as key value pairs. Non-relational databases are important when you need your data to be structured and consistent.
5. Explain the difference between replication and sharding in database management
Ans - Replication is making copies of your existing database. The new databases imitate the properties and features of the existing database. Replication is a process commonly used to manage tasks that require similar prioritizing and execution. If a particular database system collapses, replication ensures redundancy exists, so that vital data isn’t lost in transition.
Sharding is a technique used to fragment a massive database.Sharding is especially useful when large database systems encounter problems in performing tasks owing to their massive size. Sharding helps customize your database structure to make it function appropriately.
6. What are the various types of documentation in systems design?
a. Program documentation
b. System documentation
c. User documentation
d. Operations documentation
7. Which are the important structure tools employed in systems design?
a. Decision Trees
c. Data dictionary
d. Data flow diagrams
Additional system design questions for technical interviews
8. How would you design a recommendation system?
9. How do you design a traffic control service?
10. Design a messenger service like Facebook Messenger. Design a location-based service like Uber.
11. Explain the requirements of a garbage collection system design.
12. Explain the method to design a shared drive like Google Drive or Dropbox
13. Explain the process and method to design a web crawler.
14. Explain how to design an API rate limiter.
15. Design a URL shortener.
Did you know that several top companies frequently ask candidates behavioral questions as part of the interview process? Check out these Top Behavioral Questions asked at FAANG companies.
Technical interview questions on coding and algorithms
1. For a given string ‘A’, partition ‘A’ such that each substring is a palindrome.
2. For a given string ‘A’ and a dictionary (of words) in string ‘B’, depict if string ‘A’ can be segmented into a space-separated sequence of 1 or more dictionary words.
3. Return the multiplication of two numbers represented as strings.
4.Write code in a programming language of your choice to implement your own hashtable.
5. Write appropriate code to demonstrate how to implement three stacks in an array.
6. For a given binary search tree, find the nth smallest element.
7. Write a function, Fib(), that takes Integer N and returns the nth Fibonacci number in the sequence.
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