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North Point Technology Interview Questions

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Data Structures & Algorithms

Given an integer N, write a function that returns all of the prime numbers up to N

Prime to N

This problem involves identifying duplicate numbers in a list of integers. The function should return a list of the duplicate numbers.

Find Duplicate Numbers in a List

Write a program in python to determine the TF values for each term of a document

Term Frequency

Swap the values of `a` and `b` in the dictionary without declaring any other variable

Swap Variables

This question requires the implementation of the Fibonacci sequence using three different methods: recursively, iteratively, and using memoization.

Implementing the Fibonacci Sequence in Three Different Methods

Machine Learning

What are some machine learning methods for building this system

FAQ Matching

Explain the key differences between classification models and regression models

Classification and Regression

Bias vs. Variance Tradeoff

How would you decide between composition and inheritance when modeling different seller types on eBay?

Seller Type Modeling

Behavioral

Describing a data project and its challenges

Hurdles In Data Projects

How would you answer when an Interviewer asks why you applied to their company?

Why Do You Want to Work With Us

What do you tell an interviewer when they ask you what your strengths and weaknesses are?

Your Strengths and Weaknesses

DevOps

Design a cloud-agnostic CI/CD pipeline supporting safe deployments and rollbacks across multiple providers.

Cloud-Agnostic Deployments

How would you structure a safe deployment process with effective stakeholder communication and rollback plans?

Safe Deployments

Design a highly available, scalable Azure infrastructure using Terraform and Kubernetes.

Azure Kubernetes Infrastructure

Write a query to get the largest salary of any employee by department

Largest Salary by Department

Compute the cumulative sales for each product.

Cumulative Sales By Product

HR Salary Reporting

Given an integer <code>N</code>, write a function that returns a list of all of the prime numbers up to <code>N</code>.

Note: Return an empty list there are no prime numbers less than or equal to <code>N</code>.

Example:

Input:

<pre tabindex="0" class="chroma"><code>N = 3
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>def prime_numbers(N) -&gt; [2,3]
</code></pre>

Given a table called <code>employees</code>, get the largest salary of any employee by department

Example:

Input:

<code>employees</code> table

<table>
<thead>
<tr>
<th>Column</th>
<th>Type</th>
</tr>
</thead>

<tbody>
<tr>
<td><code>id</code></td>
<td>INTEGER</td>
</tr>

<tr>
<td><code>department</code></td>
<td>VARCHAR</td>
</tr>

<tr>
<td><code>salary</code></td>
<td>INTEGER</td>
</tr>
</tbody>
</table>
Output:

<table>
<thead>
<tr>
<th>Column</th>
<th>Type</th>
</tr>
</thead>

<tbody>
<tr>
<td><code>department</code></td>
<td>VARCHAR</td>
</tr>

<tr>
<td><code>largest_salary</code></td>
<td>INTEGER</td>
</tr>
</tbody>
</table>

Tell me about a data project that didn’t go the way you expected. What did you set out to do, what surprised you, and how did you handle it?

Let’s say you’re given all the different marketing channels along with their respective marketing costs at a company called Mode, that sells B2B analytics dashboards.

What metrics would you use to determine the value of each marketing channel?

When determining the value of each marketing channel for the company Mode, which metric is considered the key metric?

When determining the value of each marketing channel for the company Mode, which metric is considered the key metric?

Marketing Channel Metrics

What metrics would you use to determine the value of each marketing channel?

Analytics

Given a list of integers, identify all the duplicate values in the list. Assume that the list can contain both positive and negative numbers, and the order of the list does not matter. A number is considered a duplicate if it appears more than once in the list. Return a list of the duplicate numbers.

Example 1:

Input:

<pre tabindex="0" class="chroma"><code>nums = [1, 2, 3, 1, 2, 3]
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>find_duplicates(nums) -&gt; [1, 2, 3]
</code></pre>

The numbers 1, 2, and 3 all appear more than once in the list, so they are considered duplicates.

Example 2:

Input:

<pre tabindex="0" class="chroma"><code>nums = [1, -1, 2, 3, 3, -1]
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>find_duplicates(nums) -&gt; [-1, 3]
</code></pre>

The numbers -1 and 3 both appear more than once in the list, so they are considered duplicates. Note that the order of the output does not matter.

Example 3:

Input:

<pre tabindex="0" class="chroma"><code>nums = [1, 2, 3, 4, 5]
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>find_duplicates(nums) -&gt; []
</code></pre>

None of the numbers in the list appear more than once, so there are no duplicates.

Say you are given a text document in the form of a string with the following sentences:

Example:

Input:

<pre tabindex="0" class="chroma"><code>document = &#34;I have a nice car with a nice tires&#34;
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>
{
&#34;I&#34;:0.11,
&#34;have&#34;:0.11,
&#34;a&#34;:0.22,
&#34;nice&#34;:0.22,
&#34;car&#34;: 0.11,
&#34;with&#34;:0.11,
&#34;tires&#34;:0.11
}
</code></pre>

Write a program in python to determine the TF (<code>term_frequency</code>) values for each term of this document.

Note: Round the term frequency to 2 decimal points.

You are working with the sales team of an e-commerce store to analyze their monthly performance.

They give you the <code>sales</code> table that tracks every purchase made on the store. The table contains the columns <code>id</code> (purchase id), <code>product_id</code>, <code>date</code> (purchase date), and <code>price</code>.

Write a SQL query to compute the cumulative sum of sales for each product, sorted by product_id and date.

Note: The cumulative sum for a product on a given date is the sum of the price of all purchases of the product that happened on that date and on all previous dates.

<h3>Example:</h3>

Input:

<code>sales</code> table

<table>
<thead>
<tr>
<th>Column</th>
<th>Type</th>
</tr>
</thead>

<tbody>
<tr>
<td>id</td>
<td>INTEGER</td>
</tr>

<tr>
<td>product_id</td>
<td>INTEGER</td>
</tr>

<tr>
<td>date</td>
<td>DATE</td>
</tr>

<tr>
<td>price</td>
<td>FLOAT</td>
</tr>
</tbody>
</table>
Output:

<table>
<thead>
<tr>
<th>Column</th>
<th>Type</th>
</tr>
</thead>

<tbody>
<tr>
<td>product_id</td>
<td>INTEGER</td>
</tr>

<tr>
<td>date</td>
<td>DATE</td>
</tr>

<tr>
<td>cumulative_sum</td>
<td>FLOAT</td>
</tr>
</tbody>
</table>

Let’s say that you work on the revenue forecasting team at a company like Facebook.

An executive comes to you asking about how much revenue Facebook will make in the coming year.

How would you forecast revenue for the next year?

How would you forecast revenue for the next year

Forecasting New Year Revenue

Forecasting & Time Series

Let’s say that we want to build a chatbot system for frequently asked questions. Whenever a user writes a question, we want to return the closest answer from a list of FAQs.

What are some machine learning methods for building this system?

Given an integer <code>n</code>, return the number of trailing zeroes in <code>n!</code>.

Note that <code>n! = n * (n - 1) * (n - 2) * ... * 3 * 2 * 1</code>.

<h3>Example 1</h3>

Input:

<pre tabindex="0" class="chroma"><code>n = 5
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>def trailingZeroes(n) -&gt; 1
</code></pre>

Explanation:

<pre><code>5! = 120, one trailing zero.
</code></pre>

<h3>Example 2</h3>

Input:

<pre tabindex="0" class="chroma"><code>n = 10
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>def trailingZeroes(n) -&gt; 2
</code></pre>

Explanation:

<pre><code>10! = 3,628,800 -&gt; two trailing zero.
</code></pre>

<h3>Constraints:</h3>

<ul>
<li><code>0 &lt;= n &lt;= 10^4</code></li>
</ul>

Return the number of trailing zeroes in n factorial

Factorial Trailing Zeroes

What are the key differences between classification models and regression models?

What is the MOST important difference between regression and classification models?

What is the MOST important difference between regression and classification models?

Classification vs Regression

Imagine you are asked to build a machine learning model to decide new loan approvals for a
financial firm. You ask the data department in the company for a subset of data to get started
working on the problem. The data includes different features about applicants such as age,
occupation, zip code, height, number of children, favorite color, etc. You decide to build
multiple machine learning models to test out different ideas before settling on the best one.

How would you explain the bias-variance tradeoff with regards to
building and choosing a model to use?

You are given a dictionary with two keys <code>a</code> and <code>b</code> that hold integers as their values.

Without declaring any other variable, swap the value of <code>a</code> with the value of <code>b</code> and vice versa.

Note: Return the dictionary after editing it.

Example:

Input:

<pre tabindex="0" class="chroma"><code>numbers = {
 &#39;a&#39;:3,
 &#39;b&#39;:4
}
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>def swap_values(numbers) -&gt; {&#39;a&#39;:4,&#39;b&#39;:3}
</code></pre>

The Fibonacci sequence is a series of numbers in which each number is the sum of the two preceding ones, usually starting with 0 and 1. It is often used in algorithm examples, and is defined by the following formula: F(n) = F(n-1) + F(n-2), with F(0) = 0 and F(1) = 1.

Your task is to implement the Fibonacci algorithm in three different methods:
1. Recursively
2. Iteratively
3. Using Memoization

Example 1:

Input:

<pre tabindex="0" class="chroma"><code>n = 5
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>fibonacci(n) -&gt; 5
</code></pre>

Example 2:

Input:

<pre tabindex="0" class="chroma"><code>n = 10
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>fibonacci(n) -&gt; 55
</code></pre>

The Fibonacci sequence starts as follows: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55…

Given a list of integers, write a function that returns the maximum number in the list. If the list is empty, return <code>None</code>.

Example 1:

Input:

<pre tabindex="0" class="chroma"><code>nums = [1, 7, 3, 5, 6]
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>find_max(nums) -&gt; 7
</code></pre>

Example 2:

Input:

<pre tabindex="0" class="chroma"><code>nums = []
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>find_max(nums) -&gt; None
</code></pre>

The task is to write a function that takes a list of integers as input and returns the maximum number in the list. If the list is empty, the function should return `None`.

Finding the Maximum Number in a List

Let’s say you’re a software engineer on the Amazon retail website team, and over the past hour, the site has experienced a surge in traffic from thousands of suspicious IP addresses, leading to frequent outages and slow page loads for normal shoppers.

How would you analyze and respond to this potential DDoS attack, and what steps would you take to prevent similar incidents in the future?

How would you investigate and mitigate a DDoS attack impacting Amazon's website?

DDoS Attack Response

Responsible AI & Security

The HR department in your organization wants to calculate employees’ earnings.

Write a query to report the sum of regular salaries, overtime pay, and total compensations for each role.

Example:

Input:

<code>employees</code> table

<table>
<thead>
<tr>
<th>Column</th>
<th>Type</th>
</tr>
</thead>

<tbody>
<tr>
<td><code>employee_id</code></td>
<td>INTEGER</td>
</tr>

<tr>
<td><code>job_title</code></td>
<td>VARCHAR</td>
</tr>

<tr>
<td><code>salary</code></td>
<td>FLOAT</td>
</tr>

<tr>
<td><code>overtime_hours</code></td>
<td>INTEGER</td>
</tr>

<tr>
<td><code>overtime_rate</code></td>
<td>FLOAT</td>
</tr>
</tbody>
</table>
Output:

<table>
<thead>
<tr>
<th>Column</th>
<th>Type</th>
</tr>
</thead>

<tbody>
<tr>
<td><code>job_title</code></td>
<td>VARCHAR</td>
</tr>

<tr>
<td><code>total_salaries</code></td>
<td>FLOAT</td>
</tr>

<tr>
<td><code>total_overtime_payments</code></td>
<td>FLOAT</td>
</tr>

<tr>
<td><code>total_compensation</code></td>
<td>FLOAT</td>
</tr>
</tbody>
</table>

Let’s say that you’re in charge of an e-commerce D2C business that sells socks.

What business health metrics would you care about tracking on a company dashboard?

Let’s say that you're in charge of an e-commerce D2C business that sells socks. What business health metrics would you care?

D2C Socks e-Commerce

Given a string, write a function to determine if it is palindrome or not.

Note: A palindrome is a word/string that is read the same way forward as it is backward, e.g. <code>&#39;reviver&#39;</code>, <code>&#39;madam&#39;</code>, <code>&#39;deified&#39;</code> and <code>&#39;civic&#39;</code> are all palindromes, while <code>&#39;tree&#39;</code>, <code>&#39;music&#39;</code> and <code>&#39;person&#39;</code> are not palindromes.

Example:

Input:

<pre tabindex="0" class="chroma"><code>word1 = &#34;tree&#34;
word2 = &#34;radar&#34;
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>def is_palindrome(word1) -&gt; False
def is_palindrome(word2) -&gt; True
</code></pre>

Given a string, write a function to determine if it is palindrome or not.

String Palindromes

Given a string <code>s</code>, imagine reading through it one character at a time, as if you’re following a path made of letters. As you move forward, you want to keep track of the longest stretch you can travel without encountering the same character twice. String <code>s</code> consists of English letters, digits, symbols and spaces.

Your task is to find the length of the longest substring without duplicate characters — in other words, the longest continuous portion of <code>s</code> where every character is unique and no repeats interrupt the journey.

<h3>Example 1:</h3>

Input:

<pre tabindex="0" class="chroma"><code>s = &#34;xyzxyzyyxxxx&#34;
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>def longest_substring_length(s) -&gt; 3
</code></pre>

Explanation: The answer is <code>&#34;xyz&#34;</code>, with the length of 3. Note that <code>&#34;yzx&#34;</code> and <code>&#34;zxy&#34;</code> are also correct answers.

<h3>Example 2:</h3>

Input:

<pre tabindex="0" class="chroma"><code>s = &#34;xxxxxxxxxxxxxx&#34;
</code></pre>

Output:

<pre tabindex="0" class="chroma"><code>def longest_substring_length(s) -&gt; 1
</code></pre>

Explanation: The answer is <code>&#34;x&#34;</code>, with the length of 1.

<h3>Constraints:</h3>

<ul>
<li><code>0 &lt;= s.length &lt;= 5 * 10^4</code></li>
</ul>

The Longest Journey

When an interviewer asks a question along the lines of:

<ul>
<li>What would your current manager say about you? What constructive criticisms might he give?</li>
<li>What are your three biggest strengths and weaknesses you have identified in yourself?</li>
</ul>

How would you respond?

When asked about your strengths in an interview, what is an effective way to respond?

When asked about your strengths in an interview, what is an effective way to respond?

Your Strengths and Weaknesses I

Which of the following is an acceptable strategy when discussing weaknesses in an interview?

Which of the following is an acceptable strategy when discussing weaknesses in an interview?

Your Strengths and Weaknesses II

Let’s say we’re building a system for eBay to support multiple types of sellers: individuals, small businesses, and enterprise merchants. Each seller type shares core attributes like <code>seller_id</code> and <code>account_status</code>, but has unique features—enterprise merchants, for example, can manage up to 50 sub-accounts, while individuals have simpler profiles.

How would you decide between using composition or inheritance to model these seller types, and what trade-offs would you weigh in making your choice?

When an interviewer asks you a question along the lines of:

<ul>
<li>Why did you apply to our company?</li>
<li>What are you looking for in your next job?</li>
<li>What makes you a good fit for our company?</li>
</ul>

How should you respond?

When asked 'What are you looking for in your next job?' in an interview, how can you tie the company's employee benefits into your response?

When asked 'What are you looking for in your next job?' in an interview, how can you tie the company's employee benefits into your response?

Why Do You Want to Work With Us I

How can company values be used effectively in an interview when asked 'What makes you a good fit for our company?'

How can company values be used effectively in an interview when asked 'What makes you a good fit for our company?'

Why Do You Want to Work With Us II

When responding to the question 'Why did you apply to our company?' during an interview, what aspect should you highlight?

When responding to the question 'Why did you apply to our company?' during an interview, what aspect should you highlight?

Why Do You Want to Work With Us III

You work as a DevOps engineer for a global SaaS company with services deployed across multiple cloud providers. The team wants to implement a cloud-agnostic CI/CD pipeline that supports safe, zero-downtime deployments for critical microservices. The deployment process should allow for rapid rollback, controlled traffic shifting, and minimal service disruption.

How would you design this CI/CD and deployment system?

You have been tasked with designing three classes: <code>text_editor</code>, <code>moving_text_editor</code>, and <code>smart_text_editor</code>. These classes are to be created with specific functionalities as defined below:

<ol>
<li><code>text_editor</code> class:

<ul>
<li><code>write_line(string:str)</code>: A method which appends a given string to the end of the existing string.</li>
<li><code>delete_line(char_num : int)</code>: A method which deletes <code>char_num</code> number of characters from the existing string, starting from the end. If there are no characters left, the method should do nothing.</li>
<li><code>special_operation()</code>: A method which currently does nothing.</li>
<li><code>get_notes()</code>: A method which returns the internal string.</li>
</ul></li>

<li><code>moving_text_editor</code> class:

<ul>
<li>This class extends <code>text_editor</code>. The <code>special_operation()</code> method is overridden. Initially, the cursor will be at the end of the current string. If <code>special_operation()</code> is called, it moves the cursor to the beginning of the string, any additional appends will be appended to the beginning of the string instead. Calling <code>special_operation()</code> again reverses the cursor operation.</li>
</ul></li>

<li><code>smart_text_editor</code> class:

<ul>
<li>This class extends <code>text_editor</code>. In this class, the <code>special_operation()</code> method is overridden to serve as an undo operation, allowing it to undo an infinite number of operations.</li>
</ul></li>
</ol>

<h3>Input</h3>

<pre tabindex="0" class="chroma"><code>[[&#39;special_text_editor&#39;], [&#39;write_line&#39;, &#39;special_operation&#39;, &#39;write_line&#39;], [&#39;World&#39;, &#39;Hello, &#39;]]
</code></pre>

<h3>Output</h3>

<code>&#34;Hello, World&#34;</code>

Create a text editor while displaying method overriding as a concept.

Text Editor With OOP

Design Patterns

Let’s say we’re responsible for deploying a new version of Uber’s routing system, and the release includes both backend and frontend changes that may impact user workflows.

How would you design the deployment process to minimize risk, ensure clear communication with both clients and internal teams, and handle rollbacks if unexpected issues arise?

You work as a cloud architect at a large enterprise. The company is migrating its core web application to Microsoft Azure and wants to ensure high availability and scalability. You are asked to provision the infrastructure as code, leveraging Kubernetes for orchestration and Terraform for automation.

How would you architect this system to maximize reliability and scalability?

Write a technical design document describing your approach.

Let’s say you are working on Google Docs. A product manager comes to you and asks how the product is doing. 

What are the top five metrics that you would start tracking to understand the health of Google Docs?

What are the top five metrics you would start tracking to understand the health of Google Docs

Docs Metrics

Product Sense & Metrics

Challenge

<h3>Job Description</h3><div>Job Description<div>This job requires active TS/SCI clearance with a CI Polygraph. Please apply only if you have an active TS/SCI clearance with a CI Polygraph. Business Analyst / Requirements Engineer – SeniorPosition / LCAT: Business Analyst / Requirements Engineer Level: Senior Lead Designation: N/A Location: Fort Belvoir, VARole SummaryMeets with stakeholders at all levels to capture, define, develop, and document customer requirements from initial gathering through final production acceptance for applications and IT systems. Reviews and maps business processes for new applications and supports enhancements to existing systems. Analyzes and models existing business procedures to identify areas of improvement, creates detailed business requirement documentation, and partners with development teams to support delivery of software solutions.Responsibilities<ul><li>Meet with stakeholders at all levels to capture, define, develop, and document customer requirements from initial gathering through final production acceptance for applications and IT systems</li><li>Review and map business processes for new applications and to support enhancements to existing systems</li><li>Analyze and model existing business procedures to identify areas of improvement</li><li>Create Assessment Reports outlining requirements collected from stakeholder meetings during each stage of the project</li><li>Create detailed business requirement documentation</li><li>Create detailed workflows and process diagrams, including application wireframes and projected plan layouts to support customer requirements</li><li>Perform feasibility analysis and collaborate with the project management team to prioritize deliverables</li><li>Partner with the development teams to provide reporting on the status of software development solutions</li><li>Provide recommendations for improvement or technology strategies that can be leveraged for projects</li><li>Review project scope requirements and provide recommendations to the Government on possible courses of action</li><li>Provide user training and project transition support</li><li>Document current business processes as well as desired applications</li><li>Provide knowledge transfer of requirements to application developers and project managers</li></ul>Required Qualifications<ul><li>Eight years of experience as a Business Analyst capturing and documenting business processes and requirements</li><li>Six years of experience as a Business Analyst capturing and documenting software development and Information Technology processes and requirements used in a Microsoft SharePoint and Microsoft Internet Information Services (IIS) environment using the Microsoft .NET framework</li><li>Eight years of experience creating process diagrams and flow charts, mapping business processes to customer requirements</li><li>Five years of experience working with software developers and customers to scope projects, estimate levels of effort, and evaluate customer requirements to create applications to deploy to Microsoft SharePoint (both out-of-the-box and with custom coded) and to Microsoft Internet Information Services (IIS) using the Microsoft .NET Framework</li><li>Three years of experience mentoring junior personnel on proper practices and procedures</li><li>Five years of experience with the SDLC and Agile processes</li><li>TS/SCI clearance with SBI and ability to attain SI, TK, G, HCS, and NATO Secret clearance</li></ul>Preferred Qualifications<ul><li>Experience with application wireframing tools and process diagramming software</li><li>Experience supporting Agile and SCRUM development teams</li></ul><div>North Point Technology is THE BEST place to work for curious-minded engineers motivated to support our country's most crucial missions! We focus on long term projects, leveraging the latest technology in support of innovative solutions to solve our customer's most difficult problems.At North Point Technology, EMPLOYEES come first! We value our employees by providing excellent compensation, benefits, and a flexible work-life balance. We strive for a close-knit and open atmosphere where the owners are always directly available to our team members. Come join us! Apply with North Point Technology today! For positions requiring a federal security clearance, your clearance level must be clearly identified on your resume.</div></div></div>

Calculate Moving Average	SQL	Easy
Predict Customer Churn	Machine Learning	Medium
A/B Test Significance	Statistics	Medium
Optimize Query Performance	SQL	Hard
Feature Importance Analysis	Machine Learning	Medium
Clean Missing Data	Python	Easy
Neural Network Architecture	Deep Learning	Hard
Calculate Cohort Retention	SQL	Medium
Bayesian Probability	Statistics	Easy
Recommend Similar Products	Machine Learning	Hard

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