Square Interview Questions

Square is one of the most popular digital payments and financial services companies in the US. As of 2020, its total assets and revenue exceeded $9 Billion. Square employs just over 5,000 employees and consistently ranks in the list of best tech companies to work for. It offers an exciting and culturally diverse work environment that greatly values inclusion and integrity.

Being a billion-dollar tech startup, Square consistently hires top engineering talent to power its financial services and digital payments. The interview process is standard and seeks to evaluate candidates’ command in object-oriented programming languages, data structures, algorithms, and concepts in distributed systems.

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If you are preparing for an interview with Square, this article will give you an idea of the type of questions to expect at Square’s technical interview. This article will cover interview questions on coding, systems design, as well as behavioral interview questions.

Here’s a quick look at what we’ll discuss:

• The Square interview process
• Square software engineer interview questions
• Tips to crack the Square software engineer interview
• Square interview questions FAQs

The Square Interview Process

The Square technical interview process fundamentally tests your programming capabilities as an engineer. The interview process is pretty standard, consisting of coding rounds, distributed systems rounds, and behavioral and soft-skill rounds. Let’s take a look at the interview process in detail.

The Initial Screen

This is an informal round where a recruiter will get in touch with you after you’ve applied for the position through LinkedIn or any other platform. You’ll be asked a few basic questions on your experience, past organizations you’ve worked with, your skillset, and compensation details. If your profile aligns with the requirements of the position, you’ll be invited to the technical phone screen interview.

The Technical Screen

This round fundamentally aims to test if your programming and problem-solving skills are up to standard. Square delivers services at scale, and requires its core tech team to come up with optimal solutions to ensure seamless delivery of its services.

The technical phone screen is usually a remote round where your knowledge of data structures and algorithms is evaluated through one or two coding problems. This round involves writing code that executes the solution optimally. If your problem-solving skills are up to standard post evaluation, you’ll be invited for the on-site interview.

The On-Site Interview

The on-site interview is the final stage that consists of a series of interviews covering coding, systems design, and behavioral and soft-skill questions. A typical software engineer on-site interview at Square will include:

1. A coding round, where you’re asked to solve a problem on DSA by writing code. Your knowledge of various concepts in algorithms is tested in this round.
2. A design round, where you’re asked questions on scalable systems and applications. Questions around caching, network protocols and security, scaling systems, and case studies can be expected in this round.
3. A behavioral round, where your experience with past organizations, workplace-related circumstances, and general traits of your personality are evaluated to determine if you’re the right fit for the position.

Square Software Engineer Interview Questions

This section will cover sample interview questions that you can expect at the Square interview. It will cover coding, systems design, and behavioral interview questions.

Square Coding Interview Questions for Software Engineers

Coding questions essentially test your knowledge of core data structures and algorithms. Below are the important concepts you need to be well-versed with for the coding interview at Square:

• Sorting algorithms — quicksort, merge sort, heap sort, etc.
• Arrays, strings, and linked lists
• Recursion
• Trees and graphs
• Hash tables and queues
• Graph algorithms, including greedy algorithms
• Dynamic programming

Below are some sample coding interview questions asked at the Square interview:

1. Given a string s containing a set of words, transform it such that the words appear in the reverse order. One or more spaces separate words in s. (Solution)
2. Given an unsorted set of numbers from 1 to N with exactly two missing numbers, find those two missing numbers. (Solution)
3. You are given an array of integers, arr, of size n, analogous to a continuous stream of integers input. Your task is to find K largest elements from a given stream of numbers. (Solution)
4. Given a sequence, return its next lexicographically greater permutation. If such a permutation does not exist, then return it in ascending order. (Solution)
5. a) Given A Graph, Build A New One With Reversed Edges b) Given a strongly connected directed graph, build a new graph with the same number of nodes but every edge reversed. This is also called transposing a graph. (Solution)
6. Implement an iterator over a binary tree with integer values. Your iterator will be initialized with the root node. 1. next() method must return the next number in the in-order traversal of the tree. 2. hasNext() method must return whether the next element exists. (Solution)
7. Given an integer array arr of size n, find all magic triplets in it. A Magic triplet is a group of three numbers whose sum is zero. (Solution)
8. Given a binary tree “T,” write a code to generate the mirror image of the tree. (Solution)
9. Given a variety of coin types defining a currency system, find the minimum number of coins required to express a given amount of money. Assume an infinite supply of coins of every type. (Solution).
10. Given a partially filled two-dimensional integer array, fill all the empty cells such that each row, each column, and each 3 x 3 subgrid (as highlighted below by bolder lines) has every digit from 1 to 9 exactly once. (Solution)

For more coding interview questions along with the most optimal code solutions, check out our Problems Page.

Square Systems Design Interview Questions for Software Engineers

Square’s service offering is built on scalable applications and systems that reach millions of users each day. At the technical interview, your knowledge of core distributed systems is closely evaluated. Below is the list of systems design topics that are important for the Square interview:

• Databases
• Network protocols
• Systems processing
• Systems design case studies
• Caching and sharding
• Concurrency
• API modeling

Below are some sample Square interview questions on distributed systems design:

1. How do you build a file-sharing system like Dropbox?
2. How would you ensure that transactions made through Square are secure?
3. What are the network protocols to follow while building scalable payments systems?
4. How would you design a notification service that alerts users when transactions are made?
5. How would you go about designing a comprehensive chatbot service?
   

Square Behavioral Interview Questions

Behavioral traits and soft skills are also important aspects that are evaluated in technical interviews. Behavioral questions are usually around:

• Leadership
• Workplace relationships and conduct
• Past experiences
• Ethics and morality

Below are some sample Square behavioral interview questions:

1. How do you ensure to avoid distractions at work?
2. Why do you want to make the switch from your (current) company to Square?
3. Tell us about the most difficult project you worked on?
4. Have you missed project deadlines in the past?
5. Tell us about a time when you disagreed with a superior’s strategy?
6. Tell us about a time when you had to take a big project decision and how it turned out.
7. What are your thoughts about workplace inclusion?
8. How important are relationships with coworkers? Tell us about a time when a coworker was uncooperative and refused to assist you with a task.

Tips to Crack the Square Software Engineer Interview

In order to crack the Square technical interview, your prep has to be thorough. These tips will help you ace your upcoming Square software engineer interview:

• Begin your interview prep at least 8 weeks before your interview. This will give you enough time to cover the extent of topics in coding and systems design.
• Spend at least a week preparing responses to behavioral questions.
• Identify patterns in coding problems that you solve and apply patterns while solving new problems.
• Practice mock interviews with hiring managers from FAANG companies. Always make sure you practice with individuals who can give you the right feedback.
• Be consistent with your strategy and stick to it.
• Think out your solution aloud to give the interviewer a window into your thoughts. You get points not only for getting the solution right but also for your approach.

Square Interview Questions FAQs

Q. How important are systems design interviews at Square?

Systems design is an integral component of the interview process. There can be two systems design rounds in the on-site round, with questions mostly around scalable systems and applications, network protocols, databases, caching and sharding, and systems design case studies. Systems design interviews at Square are more critical for senior developer and managerial (engineering management) positions.

Q. What type of questions are asked at Square’s behavioral interviews?

Behavioral interview questions asked at Square’s technical interview are mostly around past experiences with challenging projects, relationships with coworkers and superiors, work-life balance, productivity, and general workplace-related situations. You can also be asked questions about your strengths and weaknesses and how you’d manage stress and pressure in the face of demanding work projects.  

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