Home on Arpit J | Notes

Questions that will probably come back

Fri, 03 Oct 2025 02:06:53 +0530

1. Get distinct employee names in a company using Java 8 Streams API #

Requirements

Company class
Employee class

Company can have multiple employees.

Objective
Return a list of the names of distinct employees in the company which have an ID greater than a given numeric ID.

public class Employee implements EmployeeInterface {
    private String id;
    private String name;

    public Employee(String id, String name) {
        this.id = id;
        this.name = name;
    }

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }
}

public class Company implements CompanyInterface {
    private List<Employee> employees;

    public Company(List<Employee> employees) {
        this.employees = employees;
    }

    public List<Employee> getEmployees() {
        return employees;
    }

    // originally implemented using Set
    // and .toSet() but this is better:
    public List<String> getEmployeesBasedOnEmployeeId(String idThreshold) {
        int threshold = Integer.parseInt(idThreshold);

        return employees.stream()
            .filter(employee -> Integer.parseInt(employee.getId()) > threshold)
            .map(employee -> employee.getName())
            .distinct()
            .collect(Collectors.toList());
    }
}

2. Maximum sub-array sum (Kadane’s algorithm) #

--- loop ---
1. maximum = Math.max(maximum + arr[i], arr[i]);
2. ans = Math.max(ans, maximum);

Include current element in maximum sum OR start maximum from current element (will happen when maximum till last element < 0).
Update ans

Hint on doing this for a circular list: minimising the sub-array sum.

atoi()

Thu, 27 Mar 2025 00:00:00 +0000

LC8 took all of my time today. Pseudocoding here for reference later –

Problem Statement #

Convert a string to integer -

Leading whitespaces to be ignored
+ or - to be taken into account for the integer sign
Non-digit characters to be ignored
Digit characters to be converted to integers
Constraint specifies a string length of 0 to 200, integer overflow is possible; answer in that case to be rounded off to the max/min integer value
Return the final signed integer

Pseudocode #

index = 0
answer = 0
sign = 1

if string length = 0, return 0

while (index < string.length AND leading whitespaces) {
    increment index
}

if (index < string.length AND current character + or -) {
    sign = 1 if '+' 
    OR
    sign = -1 if '-'
    increment index
}

while (index < string.length) {
    digit = (int) current character  ----- [- '0' in Java (some ASCII math)]
    if digit does not lie between 0 and 9, break loop

    check for integer overflow
        - MAX_INT / 10 > answer OR
        - MAX_INT / 10 == answer then last digit of MAX_INT to be less than current digit
    if integer overflow - return MAX or MIN int (check with sign)
    else add digit to answer
}

return answer

Advent of Code 2024

Mon, 02 Dec 2024 00:00:00 +0000

I have decided to challenge my problem solving by following through on Advent of Code this year.

“Advent of Code is an Advent calendar of small programming puzzles for a variety of skill levels that can be solved in any programming language you like. People use them as interview prep, company training, university coursework, practice problems, a speed contest, or to challenge each other.”

I’m solving the problems in Java since I use it at work and feel most comfortable with it. ⚠️ Caution: This Java code works… mostly. Optimization? wHAT’S THAT?
(If you’re a recruiter; just kidding.)

How to fix messed up internal VPN on Ubuntu

Mon, 09 Sep 2024 00:00:00 +0000

For legal and sanity reasons, there’s no classified stuff here. To anyone from work: Yes, I fixed it. Crisis averted, lesson learnt.

This is mostly a note to self in case I try to fix this issue when it happens again, and I need to revert everything.

Problem #

WiFi works 10/10 on work laptop. VPN works 5/10. It connects, works for a few minutes and then it just stops working. Even after disconnecting from VPN, WiFi does not work normally and a system reboot is needed.

A/B Testing 101

Thu, 13 Jun 2024 00:00:00 +0000

Since this year started, I have been working on a project on controlled online experimentation system implemented from scratch, christened:
Abacus: The A/B Testing Project™.
It’s currently in the SIT environment right now where I’m interning, with a few natural holdups that happen due to cross-team collaboration. Nevertheless, I’m confident we’ll take it to production soon.

Case Study #

Let’s say I bake two different batches of cookies. The first batch I call Hide n’ Sleep (my favourite), and the second I call Padhle-G (the classic). I’m not sure which batch would do better in the market if I was to sell them, so I conduct a small experiment on some 20 friends to see which cookie is more liked.
I give 10 of my twenty friends Hide n’ Sleep, and the remaining 10 get Padhle-G and let’s say

DAO Design Pattern with Spring Boot

Sun, 26 May 2024 04:04:08 +0530

It has been a couple of months to me developing a backend driven service for the organization where I’m interning. From hating the J of Java (irrationally) to easily writing complex controller classes and services with Spring Boot, this project has given me my first hands-on experience with Java, Spring Boot, and the DAO design pattern.

Spring Boot #

Spring Boot is a framework based on Java which is used to build web apps and microservices. Built on top of the Spring framework, it is used to quickly build new applications through a convention over configuration based approach to speed up development. The main Spring Boot components are:

srcdit

Tue, 06 Feb 2024 00:00:00 +0000

There was a phase when I was editing my .bashrc and .zshrc a lot. Having to edit them and then source them again and again soon became torturous. It would have been so much better if I had a tool to edit and source the files in just one step.

The best part about being someone who works with and understands software is that I can build a tool to meet this requirement myself. I worked on srcdit for a few days before getting busy with my internship, and I’m glad to announce that it’s in a half-working condition. Check it out here.

Asking questions the smart way - summarized

Tue, 09 Jan 2024 00:00:00 +0000

How To Ask Questions The Smart Way is one of my favourite pieces of text related to software development (although the learnings can be extrapolated to other fields too). I adopted it as my Bible back in first semester and have referred it to my friends and juniors in conversations around taking-help a LOT of times ever since.
I’ve also gone back to the document to read it again, but would agree to it being lengthy (it is highly recommend as an investment in yourself though).

First 4 hours of using Neovim

Thu, 23 Nov 2023 00:00:00 +0000

I’ve finally decided to give scary Vim a try after I followed a few commands online and got stuck in it 2 years ago. After hacking at it for the past 4 hours, here are some short notes from what I’ve learned researching and using neovim.

What is Vim? #

In simple words, a text editor which considers the use of mouse to navigate/edit a blasphemy.
Vim is a modal text editor (it uses different modes in which text can be manipulated). It is powerful and highly configurable. I’ve started getting my hands dirty with Neovim, which is an extensible fork of Vim through the use of highly functional plugins and comes with a better set of defaults like LSP, to support coding right out of the box.

Generating Sign Language

Mon, 16 Oct 2023 00:00:00 +0000

I’ve been working on creating a more accessible space online for the specially abled using AI/ML technologies under my university’s Centre of Excellence.

The What, Why, Who, When and Where #

About 5% of our country’s population suffers from auditory and speech impairment. Most of the educational content available on the internet caters to the “mainstream” population and lacks accessibility features for those with special needs.

In order to create a friendlier online space for them, we are working on modules which will essentially translate the content on internet into a more comprehensible form.

Why do I use Linux?

Sun, 09 Oct 2022 00:00:00 +0530

To start with a small rant on Apple and Microsoft being giant monopolies in the global market for operating systems.

On one hand, Apple boasts a fluid user experience (and ecosystem lock-in) with its macOS
And on the other hand we have Microsoft’s Windows which brags its vast support of applications and (pseudo) customizability.

Linux, however, speaks for itself.

Linux? #

Linux is a free and open source operating system (technically speaking 🤓☝️, it’s a kernel, but for the scope of this post, let’s call it an OS).

Learning to make a Temperature Converting API using Express.js

Sun, 12 Jun 2022 00:00:06 +0530

One of the first few tasks of the internship I recently got, was to develop a simple RESTful API which converted a given temperature from Farhenheit to Celsius and vice versa.

The choice of technology was left up to me. Having worked with Node and Express.js before, I decided it would be convenient for me to work on the API using these. It would be easier developing an understanding over the API structure and its nuances, without having to worry about learning the syntax of a new language.

Organizing OSDHack'22

Sat, 12 Feb 2022 17:20:52 +0530

OSDHack is an annual hackathon, organized by the Open Source Developers Community of JIIT Noida, Sector-62. Previously organized at the intra-college level, this year we decided to scale it up and host a nation-wide open hackathon. We saw registrations of 450+ participants and a whopping total of 100+ teams, which turned out to be way more than we had expected!

Everything, right from planning till execution was handled by the students of the community and it wasn’t a piece of cake. It’s been an exceptionally challenging journey, which the team navigated through with each other’s help. Despite being a tiring and draining experience, it gave us learnings that were valuable, and made us realize how big of a task it is to organize a large scale event.

Documenting my OSDCodeJam’21 experience

Mon, 22 Feb 2021 02:16:29 +0530

!!! Images broken !!!

It’s New Year’s Day. We are idling away since it’s our semester break, when around 3 a.m. in the morning, seniors from our college’s Open Source Developers Community (OSDC) made a big announcement. They had come up with a new and unique kind of event for us. OSDC was organizing its first Code Jam, OSDCodeJam’21.

OSDCodeJam #

OSDCodeJam is a fun, collaborative (intra-college, but just for this year) competition organized by our seniors from the Open Source Developers Community at Jaypee Institute of Information Technology.

KWoC'21 Project Mentee Experience

Thu, 07 Jan 2021 16:52:35 +0530

Kharagpur Winter of Code (KWoC) is an initiative by IIT Kharagpur’s Open Source Society (KOSS) for students with little to no experience (such as myself) in open source software development.

It aims to introduce students to the working of one of the most popular version control systems - Git. KWoC helps flatten the learning curve and allows students to prepare further for prestigious open source programs like Google Summer of Code (GSoC), Outreachy, Season of KDE, GNOME Internship program and others.

Resume

Mon, 01 Jan 0001 00:00:00 +0000

Feel free to look around! :)
Download my resume as a PDF from Google Drive - here, or from below

/ [pdf]