TCS

Large multinational IT services and consulting enterprise based in India.

3 Rounds ~14 Days Medium

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The Interview Loop

Recruiter Screen (30 min)

Standard fit check, behavioral questions, and resume overview.

Technical Loop (3-4 Rounds)

Deep dive into domain knowledge, coding, and system design.

Interview Question Bank

All Roles Backend Engineer 35 Cloud Engineer 34 Data Engineer 35 Data Scientist 35 DevOps Engineer 35 Frontend Engineer 35 Full Stack Engineer 35 Machine Learning Engineer 35 Product Manager 35 Software Engineer 35

All Topics Machine Learning 9 Python 4 System Design 4 SQL 4 Deep Learning 2 Statistics 2 Algorithms 2 MLOps 2

Data Scientist • Behavioral • medium

Tell me about a time you had to explain a complex machine learning model's predictions to a non-technical business stakeholder.

#Stakeholder Management #Explainable AI #Communication

Practice

Data Scientist • Behavioral • medium

Describe a situation where a client's data quality was extremely poor. How did you handle the project delivery?

#Data Quality #Client Management #Adaptability

Practice

Data Scientist • Behavioral • easy

How do you prioritize tasks when working on multiple client deliverables with conflicting deadlines?

#Prioritization #Agile #Client Delivery

Practice

Data Scientist • Behavioral • hard

Tell me about a time your model performed well in training and testing, but failed in production. What went wrong and how did you fix it?

#Production Issues #Debugging #Real-world ML

Practice

Data Scientist • Behavioral • easy

Why do you want to join TCS, and how do you align with our focus on continuous learning and delivering value to global enterprise clients?

#Company Knowledge #Motivation #Core Values

Practice

Data Scientist • Coding • medium

Write a SQL query using window functions to find the top 3 highest spending customers in each region for a retail client.

#Window Functions #DENSE_RANK #PARTITION BY

Practice

Data Scientist • Coding • easy

Write a Python function to detect if two strings are anagrams of each other, optimizing for time complexity.

#Strings #Hash Maps #Python

Practice

Data Scientist • Coding • medium

Write a Pandas code snippet to fill missing values in a 'Sales' column with the rolling 7-day average of that specific store.

#Pandas #Data Imputation #Time Series

Practice

Data Scientist • Coding • easy

Write a SQL query to find the employee who earns more than their direct manager.

#Self Join #SQL Queries

Practice

Data Scientist • Coding • medium

Given an array of integers, write a Python script to find the maximum sum of any contiguous subarray.

#Dynamic Programming #Kadane's Algorithm

Practice

Data Scientist • Coding • medium

Write a SQL query to calculate the cumulative sum of revenue per month for the year 2023.

#Window Functions #Aggregations

Practice

Data Scientist • Coding • medium

Write a Python function to merge two overlapping Pandas DataFrames based on a common ID, keeping only the updated values from the second DataFrame.

#Pandas #Data Manipulation

Practice

Data Scientist • Coding • hard

Write a SQL query to find the 3rd highest salary from an Employee table without using the LIMIT or TOP keywords.

#Subqueries #Correlated Subqueries

Practice

Data Scientist • Coding • easy

Write a Python program to extract all valid email addresses from a given large text file.

#Regex #String Parsing

Practice

Data Scientist • System Design • hard

How would you design a real-time recommendation system for a global e-commerce client?

#Recommendation Engines #Collaborative Filtering #Real-time Processing #Scalability

Practice

Data Scientist • System Design • hard

A client wants to implement a Generative AI solution to query their internal PDF documents. How would you architect this?

#GenAI #RAG #Vector Databases #LLMs

Practice

Data Scientist • System Design • medium

How do you monitor a deployed machine learning model for concept drift in a production environment?

#Model Monitoring #Concept Drift #MLOps

Practice

Data Scientist • System Design • medium

Design an architecture to deploy a Python-based ML model as a highly available REST API.

#Deployment #Docker #FastAPI #Kubernetes

Practice

Data Scientist • System Design • hard

Design a predictive maintenance system for a manufacturing client to predict machine failures before they occur.

#Predictive Maintenance #IoT #Time Series #Classification

Practice

Data Scientist • System Design • medium

Design a churn prediction pipeline for a telecom client. What features would you create and what model would you choose?

#Churn Prediction #Feature Engineering #Pipeline Design

Practice

Data Scientist • Technical • medium

How does XGBoost handle missing values internally?

#XGBoost #Missing Data #Algorithms

Practice

Data Scientist • Technical • easy

Explain the difference between Bagging and Boosting. Give an example of an algorithm for each.

#Ensemble Methods #Random Forest #XGBoost

Practice

Data Scientist • Technical • medium

Given a massive transactional dataset from a banking client, how would you handle highly imbalanced classes for a fraud detection model?

#Imbalanced Data #SMOTE #Class Weights #Fraud Detection

Practice

Data Scientist • Technical • hard

Explain the mathematical difference between L1 (Lasso) and L2 (Ridge) regularization. Why does L1 lead to sparsity?

#Regularization #Mathematics #Feature Selection

Practice

Data Scientist • Technical • medium

What is Data Leakage in machine learning? Give an example of how it might occur in a time-series forecasting project.

#Data Leakage #Time Series #Cross-validation

Practice

Data Scientist • Technical • hard

Explain the architecture of a Transformer model. What makes Self-Attention more efficient than RNNs for NLP tasks?

#Transformers #NLP #Self-Attention #LLMs

Practice

Data Scientist • Technical • medium

What is the curse of dimensionality, and how do you mitigate it in a dataset with 5000 features?

#Dimensionality Reduction #PCA #Feature Engineering

Practice

Data Scientist • Technical • medium

What are the assumptions of Linear Regression? How do you check if they are violated?

#Linear Regression #Statistics #Assumptions

Practice

Data Scientist • Technical • easy

Explain the difference between Precision and Recall. In a medical diagnosis model for a fatal disease, which one is more important?

#Evaluation Metrics #Classification

Practice

Data Scientist • Technical • medium

What is Multicollinearity? How does it affect a model, and how do you detect it?

#Multicollinearity #VIF #Feature Engineering

Practice

Data Scientist • Technical • easy

How does the K-Means clustering algorithm work? How do you choose the optimal number of clusters?

#Clustering #K-Means #Unsupervised Learning

Practice

Data Scientist • Technical • medium

What is the vanishing gradient problem in Deep Learning, and how do modern architectures solve it?

#Neural Networks #Gradients #Activation Functions

Practice

Data Scientist • Technical • medium

Explain the concept of Word Embeddings. How does Word2Vec differ from contextual embeddings like BERT?

#NLP #Embeddings #BERT #Word2Vec

Practice

Data Scientist • Technical • medium

How would you optimize a Pandas script that is currently taking 2 hours to process 10 million rows of data?

#Optimization #Pandas #Big Data

Practice

Data Scientist • Technical • medium

What is the difference between Generative and Discriminative models? Give an example of each.

#Model Types #Generative AI #Statistics

Practice

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Senior Engineer

Focuses on core competencies, system constraints, and clear communication.

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Think Out Loud

Always explain your thought process before writing code or drawing architecture.

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