Coding and Aptitude Round before interview

Coding challenges are meant to test your coding skills (especially if you are applying for ML engineer role). The coding challenges can contain algorithm and data structures problems of varying difficulty. These challenges will be timed based on how complicated the questions are. These are intended to test your basic algorithmic thinking.
Sometimes, a complicated data science question like making predictions based on twitter data are also given. These challenges are hosted on HackerRank, HackerEarth, CoderByte etc. In addition, you may even be asked multiple-choice questions on the fundamentals of data science and statistics. This round is meant to be a filtering round where candidates whose fundamentals are little shaky are eliminated. These rounds are typically conducted without any manual intervention, so it is important to be well prepared for this round.

Sometimes a separate Aptitude test is conducted or along with the technical round an aptitude test is also conducted to assess your aptitude skills. A Data Scientist is expected to have a good aptitude as this field is continuously evolving and a Data Scientist encounters new challenges every day. If you have appeared for GMAT / GRE or CAT, this should be easy for you.

Resources for Prep:

For algorithms and data structures prep,Leetcode and Hackerrank are good resources.

For aptitude prep, you can refer to IndiaBixand Practice Aptitude.

With respect to data science challenges, practice well on GLabs and Kaggle.

Brilliant is an excellent resource for tricky math and statistics questions.

For practising SQL, SQL Zoo and Mode Analytics are good resources that allow you to solve the exercises in the browser itself.

Things to Note:

Ensure that you are calm and relaxed before you attempt to answer the challenge. Read through all the questions before you start attempting the same. Let your mind go into problem-solving mode before your fingers do!

In case, you are finished with the test before time, recheck your answers and then submit.

Sometimes these rounds don’t go your way, you might have had a brain fade, it was not your day etc. Don’t worry! Shake if off for there is always a next time and this is not the end of the world.

9 tips to improve your problem-solving skills in coding:

Understand the problem before coding

Break problems into smaller parts

Practice daily on platforms like LeetCode or HackerRank

Learn common data structures and algorithms

Draw diagrams to visualize logic

Dry run your code with sample inputs

Focus on optimizing time and space complexity

Review solutions after solving a problem

Don’t fear hard problems — struggle builds skill

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100 Must do Leetcode problems 🚀

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Python Methods

Python for everything 👆

Theoretical Questions for Coding Interviews on Basic Data Structures

1. What is a Data Structure?
A data structure is a way of organizing and storing data so that it can be accessed and modified efficiently. Common data structures include arrays, linked lists, stacks, queues, and trees.

2. What is an Array?
An array is a collection of elements, each identified by an index. It has a fixed size and stores elements of the same type in contiguous memory locations.

3. What is a Linked List?
A linked list is a linear data structure where elements (nodes) are stored non-contiguously. Each node contains a value and a reference (or link) to the next node. Unlike arrays, linked lists can grow dynamically.

4. What is a Stack?
A stack is a linear data structure that follows the Last In, First Out (LIFO) principle. The most recently added element is the first one to be removed. Common operations include push (add an element) and pop (remove an element).

5. What is a Queue?
A queue is a linear data structure that follows the First In, First Out (FIFO) principle. The first element added is the first one to be removed. Common operations include enqueue (add an element) and dequeue (remove an element).

6. What is a Binary Tree?
A binary tree is a hierarchical data structure where each node has at most two children, usually referred to as the left and right child. It is used for efficient searching and sorting.

7. What is the difference between an array and a linked list?

Array: Fixed size, elements stored in contiguous memory.

Linked List: Dynamic size, elements stored non-contiguously, each node points to the next.


8. What is the time complexity for accessing an element in an array vs. a linked list?

Array: O(1) for direct access by index.

Linked List: O(n) for access, as you must traverse the list from the start to find an element.


9. What is the time complexity for inserting or deleting an element in an array vs. a linked list?

Array:

Insertion/Deletion at the end: O(1).

Insertion/Deletion at the beginning or middle: O(n) because elements must be shifted.


Linked List:

Insertion/Deletion at the beginning: O(1).

Insertion/Deletion in the middle or end: O(n), as you need to traverse the list.



10. What is a HashMap (or Dictionary)?
A HashMap is a data structure that stores key-value pairs. It allows efficient lookups, insertions, and deletions using a hash function to map keys to values. Average time complexity for these operations is O(1).

Coding interview: https://whatsapp.com/channel/0029VammZijATRSlLxywEC3X

How to create a QR Code Project with error handling in Python

import qrcode

def generate_qr_code(text, file_name):
qr = qrcode.QRCode(
version=1,
error_correction=qrcode.constants.ERROR_CORRECT_L,
box_size=10,
border=3
)

qr.add_data(text)
qr.make(fit=True)
img = qr.make_image(fill_color="#4B8BBE", back_color="white")
img.save(file_name)

if name == "main":
text = "DataSimplifier.com"
file_name = "qr_code.png"

generate_qr_code(text, file_name)
print(f"QR code saved as {file_name}")

5 Easy Projects to Build as a Beginner

(No AI degree needed. Just curiosity & coffee.)

❯ 1. Calculator App
 • Learn logic building
 • Try it in Python, JavaScript or C++
 • Bonus: Add GUI using Tkinter or HTML/CSS

❯ 2. Quiz App (with Score Tracker)
 • Build a fun MCQ quiz
 • Use basic conditions, loops, and arrays
 • Add a timer for extra challenge!

❯ 3. Rock, Paper, Scissors Game
 • Classic game using random choice
 • Great to practice conditions and user input
 • Optional: Add a scoreboard

❯ 4. Currency Converter
 • Convert from USD to INR, EUR, etc.
 • Use basic math or try fetching live rates via API
 • Build a mini web app for it!

❯ 5. To-Do List App
 • Create, read, update, delete tasks
 • Perfect for learning arrays and functions
 • Bonus: Add local storage (in JS) or file saving (in Python)


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Python Projects: https://whatsapp.com/channel/0029Vau5fZECsU9HJFLacm2a

Coding Projects: https://whatsapp.com/channel/0029VazkxJ62UPB7OQhBE502

ENJOY LEARNING 👍👍