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TCS Interview Questions 2026: 100+ Questions & Answers

Prepare for TCS interviews in 2026 with 100+ technical, HR, Java, SQL, DBMS, coding, project, behavioral, Digital and Prime interview questions with sample answers and preparation tips.

InterviewAssist Editorial Team28 September 2026 1 min read

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TCS Interview Questions 2026: 100+ Questions & Answers for Freshers and Experienced Candidates

Preparing for a TCS interview in 2026 means preparing for much more than a few HR questions.

Depending on the hiring track, role, skill selected during registration, experience level, and performance in earlier stages, a TCS interview can test your:

Resume and academic background
Final-year or professional projects
Programming fundamentals
Object-oriented programming
Java, Python, C, C++, or another primary language
DBMS and SQL
Operating systems
Computer networks
Data structures and algorithms
Coding ability
REST APIs
Cloud and microservices
Software engineering fundamentals
Problem-solving approach
Communication
Behavioral judgment
Career motivation

This guide contains 165 TCS interview questions with explanations, sample answers, follow-up questions, and preparation tips for both freshers and experienced candidates.

It is designed to help you prepare for TCS interviews in 2026 without memorizing robotic answers.

If you are also preparing with AI-based mock interviews, read our complete guide to AI interview assistants.

TCS Hiring Process in 2026

For TCS All India NQT hiring, TCS currently describes an integrated assessment consisting of a Foundation section and an Advanced section.

According to the official TCS hiring information, the current test pattern is:

Section	Subsection	Duration
Foundation	Numerical Ability	25 minutes
Foundation	Verbal Ability	25 minutes
Foundation	Reasoning Ability	25 minutes
Advanced	Advanced Quantitative & Reasoning Ability	25 minutes
Advanced	Advanced Coding	90 minutes
Total		190 minutes

TCS states that the Advanced section is especially important for candidates aspiring to Digital or Prime opportunities.

The company also notes that shortlisted candidates are evaluated predominantly on the skill selected during registration, in addition to the usual interview discussion.

Official source: TCS All India NQT Hiring

A typical journey can therefore look like:

Register on the TCS NextStep portal
Apply for the relevant drive
Appear for the TCS NQT
Complete coding sections where applicable
Get shortlisted for an interview category
Attend technical interviews
Attend managerial or business discussions where applicable
Attend HR discussion
Complete eligibility and document verification

The exact sequence may differ.

TCS Ninja, Digital and Prime: What Changes in Interview Preparation?

A common mistake is preparing the same way for every TCS opportunity.

The fundamentals overlap, but interview depth can differ considerably.

TCS Ninja

Preparation commonly emphasizes:

Strong basics
Programming fundamentals
OOP
DBMS
SQL
Projects
Communication
Basic coding
Learning ability

You should be able to explain concepts clearly and solve straightforward technical problems without becoming confused by follow-up questions.

TCS Digital

Expect stronger technical depth.

Prepare:

DSA beyond very basic questions
Java or your chosen programming language in depth
SQL optimization
APIs
Cloud fundamentals
Microservices concepts
Debugging
Project architecture
Coding
Problem solving

TCS Prime

Candidates targeting highly technical tracks should prepare for deeper engineering discussions such as:

Advanced coding
System design basics
Scalability
Concurrency
Distributed systems
Database trade-offs
Caching
Messaging
Cloud architecture
Security
Performance troubleshooting
Production engineering scenarios

Do not assume that simply knowing definitions will be enough.

How to Use This TCS Interview Guide

Do not read all 165 questions once and consider your preparation complete.

Instead, divide the article into four passes.

Pass 1 — Resume

Prepare every skill, project, internship, certification, and achievement on your resume.

Pass 2 — Fundamentals

Revise:

Programming
OOP
SQL
DBMS
OS
Networks
DSA

Pass 3 — Role-specific depth

Prepare the technologies required for the position.

Examples:

Java + Spring Boot
Python
Cloud
React
Data engineering
DevOps
Testing
Cybersecurity

Pass 4 — Mock interviews

Practice answering questions aloud.

Do not only read.

You can also use InterviewAssist for permitted practice and mock-interview workflows using your resume and job description.

TCS HR Interview Questions and Detailed Answers

1. Tell me about yourself.

This is often one of the first questions and one of the most important.

The interviewer is not asking for your entire life story.

They want a concise professional introduction.

A strong structure is:

Current status → Education/experience → Skills → Project/achievement → Career direction

Sample answer for a fresher

Sample answer for an experienced candidate

Common follow-up questions

Why did you choose Java?
Tell me more about your project.
What exactly did you build?
What was the hardest problem?
Why are you looking for a change?

Common mistake

Do not say:

unless the interviewer specifically asks for personal background.

Keep the answer professional.

2. Why do you want to join TCS?

A weak answer:

A stronger answer connects your goals with the organization.

Sample answer

What the interviewer may test

They may want to know whether you:

Researched the company
Understand the role
Have realistic career expectations
Are genuinely interested

3. What do you know about TCS?

Prepare basic information about:

Tata Consultancy Services
Tata Group
IT services and consulting
Global client delivery
AI, cloud, enterprise software, and digital transformation
Career opportunities across industries and geographies

Do not overload your answer with memorized statistics.

Use verified and recent facts if you mention numbers.

4. Why should we hire you?

Do not say:

Almost every candidate says that.

A better structure is:

Relevant ability + evidence + attitude

Sample answer

5. What are your strengths?

Choose two or three strengths.

Examples:

Problem solving
Structured thinking
Communication
Fast learning
Ownership
Persistence
Collaboration

Better answer

This is stronger because it includes evidence.

6. What is your biggest weakness?

Avoid fake weaknesses such as:

Choose something real but manageable.

Example

This demonstrates awareness and improvement.

7. Where do you see yourself in five years?

Avoid focusing only on designation.

Sample answer

8. Are you willing to relocate?

Answer honestly.

If yes:

If you have constraints, explain them professionally.

9. Are you comfortable working in shifts?

Do not say yes if you genuinely cannot.

A professional answer can be:

10. Why TCS instead of another IT company?

Focus on TCS without attacking others.

Example

11. What motivates you?

Good responses include:

Solving difficult problems
Building useful software
Learning
Improving systems
Helping teams deliver
Seeing measurable results

Example:

12. What are your salary expectations?

Fresher answer

Experienced answer

13. Are you willing to work from any TCS location?

Be factual.

If flexible:

14. Why did you choose your engineering branch?

Sample answer

15. Do you have any backlogs?

Always answer truthfully.

TCS eligibility rules can include academic conditions, so discrepancies may become a problem later.

16. Why were your marks low in one semester?

Avoid excuses.

Example

17. What makes you different from other candidates?

Do not claim you are better than everyone.

Example

18. What are your hobbies?

Use genuine hobbies.

Be ready for follow-ups.

If you say "reading," expect:

Which book did you read recently?
What did you learn from it?

19. Who inspires you and why?

Focus on the quality.

Example:

20. Do you have any questions for us?

Good questions include:

What technologies does this team currently use?
What would I work on during my first few months?
What skills differentiate people who perform well in this role?
How does the team support learning and upskilling?
What does a typical project lifecycle look like?

Avoid asking only about leave, promotion, or salary in the first question unless those topics are already part of the discussion.

TCS Resume and Project Interview Questions

Your project is one of the easiest places for an interviewer to test whether your knowledge is real.

A candidate may memorize Java definitions, but it is much harder to fake deep understanding of a project they claim to have built.

21. Explain your final-year project.

Use:

Problem → Users → Solution → Architecture → Your contribution → Result

Example answer

Follow-ups

Why Spring Boot?
Why PostgreSQL?
How did authentication work?
How did you deploy it?
How did you test it?
What would you change?

22. Why did you choose this project?

A good answer demonstrates problem awareness.

23. What exactly was your contribution?

Be precise.

Weak:

Strong:

24. Why did you choose your technology stack?

Your answer should compare alternatives.

Example:

25. What was the biggest technical challenge?

Use:

Issue → Diagnosis → Solution → Result

Example:

26. How did you design your database?

Explain:

Main entities
Relationships
Keys
Constraints
Indexes
Normalization

Example:

27. What would you improve if you built the project again?

Strong candidates can criticize their own design.

Example:

28. How would your application handle one million users?

Do not immediately say "microservices."

Start with bottlenecks.

Discuss:

Stateless application instances
Load balancer
Caching
Database indexes
Read replicas
Connection pooling
Queueing
CDN
Horizontal scaling
Observability

29. What happens if your database goes down?

Talk about:

Redundancy
Backups
Replication
Failover
Connection handling
Graceful error responses
Monitoring
Recovery testing

30. How did you test your project?

Possible categories:

Unit tests
Integration tests
API tests
UI tests
Manual tests
Load tests

Explain one test in detail.

31. Did you use Git?

Be ready to explain:

git clone
git add
git commit
git pull
git push
branches
merge
rebase
conflict resolution

32. How did your team divide work?

Explain ownership, not vague participation.

33. Did you have disagreements in your team?

Show collaboration.

A good answer includes:

What the disagreement was
How you evaluated options
How the team decided
Result

34. How did you deploy your application?

Be ready to describe the complete path.

Example:

Git repository
→ CI build
→ Docker image
→ server/cloud
→ reverse proxy
→ application
→ database

Only discuss tools you actually used.

35. How did you secure your project?

Good areas:

Password hashing
Authentication
Authorization
HTTPS
Input validation
SQL injection prevention
CORS
Secrets management
Rate limiting
Logging

TCS OOPs Interview Questions

36. What is OOP?

Object-oriented programming structures software around objects that combine state and behavior.

The most commonly discussed principles are:

Encapsulation
Abstraction
Inheritance
Polymorphism

Why interviewers ask this

They want to know whether you understand design concepts, not just Java syntax.

37. What is encapsulation?

Encapsulation means keeping internal object state controlled and exposing behavior through defined methods.

class BankAccount {
    private double balance;

    public void deposit(double amount) {
        if (amount > 0) {
            balance += amount;
        }
    }

    public double getBalance() {
        return balance;
    }
}

Why is this better than a public balance variable?

Because the class can enforce rules.

38. What is abstraction?

Abstraction hides unnecessary implementation details and exposes the behavior users of the component actually need.

Example:

When you call:

paymentService.pay(order);

the caller should not need to know every detail of network requests, retry logic, encryption, or database operations.

39. What is inheritance?

Inheritance allows a class to derive behavior and state from another class.

class Employee {
    String name;
}

class Developer extends Employee {
    String programmingLanguage;
}

Be prepared for:

No. Composition is often preferable when there is no strong "is-a" relationship.

40. What is polymorphism?

Polymorphism allows the same interface to represent different implementations.

Example:

interface PaymentProcessor {
    void pay(double amount);
}

Possible implementations:

CardPaymentProcessor
UpiPaymentProcessor
WalletPaymentProcessor

The calling code can work with the interface instead of hard-coding one implementation.

41. What is method overloading?

Same method name, different parameter lists.

int sum(int a, int b)
double sum(double a, double b)
int sum(int a, int b, int c)

42. What is method overriding?

A subclass provides its own implementation of an inherited method.

43. Overloading vs overriding?

Topic	Overloading	Overriding
Purpose	Same operation, different inputs	Replace inherited behavior
Parameters	Must differ	Same signature
Resolution	Compile time	Runtime dispatch
Inheritance needed?	No	Yes

44. What is an interface?

An interface defines a contract.

interface NotificationService {
    void send(String message);
}

Implementations can include:

EmailNotificationService
SmsNotificationService
PushNotificationService

45. Abstract class vs interface?

Use an abstract class when related classes need common implementation or state.

Use an interface when you want to define a capability independent of class hierarchy.

TCS Java Interview Questions

46. Why is Java platform independent?

Java source code is compiled into bytecode.

The JVM executes that bytecode on supported operating systems.

This leads to the classic idea:

The JVM itself is platform-specific, but Java bytecode is designed to be portable.

47. JDK vs JRE vs JVM?

JVM

Executes bytecode.

JRE

Provides the runtime environment necessary to execute Java applications.

JDK

Provides development tools such as:

Compiler
Debugger
Packaging tools
Runtime components

48. `==` vs `.equals()`?

For primitives, == compares values.

For object references, == checks whether references point to the same object.

.equals() is intended for logical equality when overridden correctly.

Example:

String a = new String("java");
String b = new String("java");

System.out.println(a == b);       // false
System.out.println(a.equals(b));  // true

49. String vs StringBuilder vs StringBuffer?

String

Immutable.

StringBuilder

Mutable and usually best for frequent string modifications in single-threaded code.

StringBuffer

Mutable and synchronized.

50. Why is String immutable?

Advantages include:

Safer sharing
Easier thread use
Stable hash codes
String pool support
Reduced accidental modification

51. ArrayList vs LinkedList?

ArrayList

Dynamic array
Fast indexed access
Appending is typically efficient
Middle insertion/removal can involve shifting

LinkedList

Doubly linked nodes
No constant-time indexed lookup
Insertions/removals can be efficient when you already have the node position
Higher per-element memory overhead

52. HashMap vs Hashtable?

HashMap

Not synchronized by default
Allows one null key
Allows null values

Hashtable

Synchronized
Does not allow null keys or values
Legacy class

For concurrent use cases, ConcurrentHashMap is usually more relevant than Hashtable.

53. How does HashMap work internally?

A simplified explanation:

hashCode() is called on the key.
The hash helps determine a bucket.
The bucket may contain one or more entries.
equals() is used to identify the correct matching key.
Java can convert heavily collided buckets into tree structures under certain conditions.

Follow-up

What happens if equals() is overridden but hashCode() is not?

Two logically equal objects may produce different hash codes, causing hash-based collections to behave incorrectly.

54. What is exception handling?

Exception handling allows code to deal with failures without crashing in uncontrolled ways.

Java commonly uses:

try
catch
finally
throw
throws

55. Checked vs unchecked exceptions?

Checked

Compiler requires handling or declaration.

Example:

IOException

Unchecked

Usually programming errors or runtime conditions.

Example:

NullPointerException
IllegalArgumentException

56. `throw` vs `throws`?

throw actually throws an exception.

throw new IllegalArgumentException("Invalid age");

throws declares that a method may propagate exceptions.

void readFile() throws IOException

57. What is multithreading?

Multithreading allows multiple threads to execute within a process.

Benefits can include:

Responsiveness
Parallel execution
Better resource use

Challenges include:

Race conditions
Deadlocks
Visibility
Synchronization complexity

58. What is synchronization?

Synchronization controls access to shared mutable state.

Example:

synchronized void increment() {
    count++;
}

But do not use synchronization blindly. It can introduce contention and performance problems.

59. What is a deadlock?

A deadlock occurs when threads wait forever for resources held by each other.

Classic conditions:

Mutual exclusion
Hold and wait
No preemption
Circular wait

60. What is garbage collection?

Garbage collection automatically reclaims memory occupied by objects that are no longer reachable.

Interviewers may follow up with:

Can Java still have memory leaks?
What is a strong reference?
What is the heap?
What triggers GC pressure?

Yes, Java applications can still leak memory logically by retaining references unnecessarily.

TCS DBMS Interview Questions

61. What is a DBMS?

A DBMS is software used to store, organize, retrieve, update, and control access to data.

Examples:

PostgreSQL
MySQL
Oracle
SQL Server

62. DBMS vs RDBMS?

RDBMS systems organize data around relations/tables and typically support:

Keys
Constraints
Relationships
SQL
Transactions

63. What is a primary key?

A primary key uniquely identifies each row.

Properties:

Unique
Not null
Stable choice where possible

64. What is a foreign key?

A foreign key creates a relationship between records in different tables.

Example:

orders.user_id → users.id

It helps maintain referential integrity.

65. What is normalization?

Normalization organizes data to reduce redundancy and avoid update anomalies.

1NF

Atomic values.

2NF

No partial dependency on part of a composite key.

3NF

No inappropriate transitive dependencies.

BCNF

A stronger form where every determinant is a candidate key.

66. What is denormalization?

Denormalization intentionally adds redundancy to improve certain query patterns.

Used carefully in:

Reporting
Analytics
Read-heavy systems

67. What are ACID properties?

Atomicity

All or nothing.

Consistency

The database moves from one valid state to another.

Isolation

Concurrent transactions behave according to isolation guarantees.

Durability

Committed data is preserved according to durability guarantees.

68. What is an index?

An index accelerates lookups by maintaining an additional data structure.

Benefits:

Faster reads
Faster filtering
Faster joins in many cases

Costs:

Extra storage
Slower inserts
Slower updates
Maintenance overhead

69. What is a transaction?

A transaction groups operations into a logical unit.

Example:

Money transfer:

Debit account A
Credit account B

Both should succeed or fail together.

70. What is a database deadlock?

Example:

Transaction A locks row 1 and waits for row 2.

Transaction B locks row 2 and waits for row 1.

Neither can continue.

Databases often detect this and abort one transaction.

TCS SQL Interview Questions

71. DELETE vs TRUNCATE vs DROP

DELETE

Removes rows.

DELETE FROM users WHERE inactive = true;

TRUNCATE

Removes all rows efficiently in many systems.

TRUNCATE TABLE users;

DROP

Removes the table itself.

DROP TABLE users;

Transaction and logging details differ by database engine.

72. WHERE vs HAVING?

WHERE filters rows before grouping.

HAVING filters groups after aggregation.

SELECT department_id, COUNT(*)
FROM employees
WHERE active = true
GROUP BY department_id
HAVING COUNT(*) > 10;

73. What is a JOIN?

INNER JOIN

Only matching rows.

LEFT JOIN

All rows from left + matching right rows.

RIGHT JOIN

All rows from right + matching left rows.

FULL OUTER JOIN

All rows from both sides.

74. Find the second-highest salary.

Simple approach:

SELECT MAX(salary)
FROM employee
WHERE salary < (
    SELECT MAX(salary)
    FROM employee
);

Window-function approach:

SELECT salary
FROM (
    SELECT salary,
           DENSE_RANK() OVER (ORDER BY salary DESC) AS rnk
    FROM employee
) t
WHERE rnk = 2;

Follow-up

Why use DENSE_RANK() instead of ROW_NUMBER()?

Because duplicate salaries may need the same rank.

75. Find duplicate emails.

SELECT email, COUNT(*)
FROM users
GROUP BY email
HAVING COUNT(*) > 1;

76. What is a subquery?

A subquery is a query nested within another query.

Example:

SELECT *
FROM employees
WHERE salary > (
    SELECT AVG(salary)
    FROM employees
);

77. UNION vs UNION ALL?

UNION removes duplicate rows.

UNION ALL keeps duplicates.

UNION ALL is usually faster because it does not need duplicate elimination.

78. What is GROUP BY?

It groups rows so aggregate functions can operate on each group.

Example:

SELECT department_id, AVG(salary)
FROM employees
GROUP BY department_id;

79. What is a stored procedure?

A stored procedure is database-side executable logic.

Potential uses:

Batch processing
Data transformations
Encapsulating business logic

Trade-offs include vendor dependence and maintainability.

80. What is a view?

A view is a stored query that behaves like a virtual table.

Example:

CREATE VIEW active_users AS
SELECT id, name, email
FROM users
WHERE active = true;

TCS Operating System Interview Questions

81. What is an operating system?

An operating system manages hardware and provides services for applications.

Responsibilities include:

Process management
Memory management
File systems
Scheduling
Device control
Networking
Security

82. Process vs thread?

Process

Own execution environment.

Thread

Execution unit within a process.

Threads commonly share:

Heap
Open resources
Process memory

while having their own stack and execution state.

83. What is context switching?

The CPU pauses one execution context and resumes another.

This requires saving and restoring state, so context switching has overhead.

84. What is virtual memory?

Virtual memory gives each process a logical address space and allows the OS to map it to physical memory.

Benefits include:

Isolation
Efficient memory management
Ability to run programs larger than available physical RAM in some scenarios

85. What is paging?

Paging divides memory into fixed-size pages and frames.

The operating system maps virtual pages to physical frames.

86. What is a semaphore?

A semaphore is a synchronization primitive represented by a counter.

It can control access to a limited number of resources.

87. Mutex vs semaphore?

Mutex

Usually one owner at a time.

Semaphore

Counter-based and can permit multiple concurrent accesses depending on count.

TCS Computer Network Interview Questions

88. What is the OSI model?

Physical
Data Link
Network
Transport
Session
Presentation
Application

Interviewers often ask what protocols or devices belong at each layer.

89. TCP vs UDP?

TCP

Connection-oriented
Reliable delivery mechanisms
Ordered byte stream
Retransmissions
Flow/congestion handling

UDP

Connectionless
Lower overhead
No built-in delivery guarantee
Useful for latency-sensitive applications

90. HTTP vs HTTPS?

HTTPS is HTTP over TLS.

It provides:

Encryption
Integrity protection
Server authentication

91. What is DNS?

DNS maps human-readable names to network records.

Example:

interviewassist.in → IP address

92. What is an IP address?

An IP address identifies a network interface.

Two major versions:

IPv4
IPv6

93. What happens when you enter a URL in a browser?

A simplified flow:

Browser parses URL
DNS resolution
TCP or QUIC connection
TLS handshake for HTTPS
HTTP request
Server processes request
Response returns
Browser parses HTML
CSS/JS/assets load
Page renders

This question can expand into:

DNS
TLS
TCP
HTTP
CDNs
Browser rendering

TCS Data Structures Interview Questions

94. Array vs linked list?

Array

Contiguous logical indexing
Fast indexed access
Resizing may require reallocation

Linked list

Node-based
Sequential traversal
Easier insertion/removal when node location is known

95. Stack vs queue?

Stack

LIFO.

Examples:

Function calls
Undo
DFS

Queue

FIFO.

Examples:

Scheduling
BFS
Message processing

96. What is a binary tree?

A tree where each node has at most two children.

97. What is a binary search tree?

For each node, keys in one subtree are ordered below the node and keys in the other above according to the chosen ordering rule.

Balanced BST:

Search ≈ O(log n)

Worst-case unbalanced tree:

O(n)

98. What is a hash table?

A hash table maps keys to buckets using a hash function.

Typical average lookup can be close to:

O(1)

assuming a reasonable hash distribution and load factor.

99. BFS vs DFS?

BFS

Queue
Level-by-level
Useful for shortest path in unweighted graphs

DFS

Stack/recursion
Explores deeply
Useful for traversal, components, cycle detection

100. What is time complexity?

Time complexity describes how algorithm work grows with input size.

Examples:

O(1)
O(log n)
O(n)
O(n log n)
O(n²)
O(2^n)

TCS Coding Interview Questions with Explanations

101. Reverse a string.

public static String reverse(String str) {
    return new StringBuilder(str).reverse().toString();
}

Without built-in reverse

public static String reverseManual(String str) {
    char[] chars = str.toCharArray();
    int left = 0;
    int right = chars.length - 1;

    while (left < right) {
        char temp = chars[left];
        chars[left] = chars[right];
        chars[right] = temp;

        left++;
        right--;
    }

    return new String(chars);
}

Time:

O(n)

102. Check whether a string is a palindrome.

public static boolean isPalindrome(String str) {
    int left = 0;
    int right = str.length() - 1;

    while (left < right) {
        if (str.charAt(left) != str.charAt(right)) {
            return false;
        }

        left++;
        right--;
    }

    return true;
}

Time:

O(n)

Space:

O(1)

103. Find the largest element in an array.

public static int max(int[] arr) {
    if (arr == null || arr.length == 0) {
        throw new IllegalArgumentException("Array cannot be empty");
    }

    int max = arr[0];

    for (int value : arr) {
        if (value > max) {
            max = value;
        }
    }

    return max;
}

104. Find the second-largest distinct element.

A good implementation should handle duplicates.

public static Integer secondLargest(int[] arr) {
    Integer largest = null;
    Integer second = null;

    for (int value : arr) {
        if (largest == null || value > largest) {
            second = largest;
            largest = value;
        } else if (value != largest &&
                   (second == null || value > second)) {
            second = value;
        }
    }

    return second;
}

105. Check whether a number is prime.

public static boolean isPrime(int n) {
    if (n < 2) {
        return false;
    }

    for (int i = 2; i * i <= n; i++) {
        if (n % i == 0) {
            return false;
        }
    }

    return true;
}

Why i * i <= n?

Because if a number has a factor greater than its square root, it must also have a factor smaller than the square root.

106. Generate Fibonacci numbers.

public static void fibonacci(int n) {
    int a = 0;
    int b = 1;

    for (int i = 0; i < n; i++) {
        System.out.print(a + " ");
        int next = a + b;
        a = b;
        b = next;
    }
}

107. Factorial of a number.

public static long factorial(int n) {
    if (n < 0) {
        throw new IllegalArgumentException("Negative input");
    }

    long result = 1;

    for (int i = 2; i <= n; i++) {
        result *= i;
    }

    return result;
}

Follow-up:

What happens for large values?

Integer overflow.

108. Find duplicates in an array.

Set<Integer> seen = new HashSet<>();
Set<Integer> duplicates = new HashSet<>();

for (int value : arr) {
    if (!seen.add(value)) {
        duplicates.add(value);
    }
}

Expected time:

O(n)

Extra space:

O(n)

109. Remove duplicates from an array.

If order must be preserved:

Set<Integer> unique = new LinkedHashSet<>();

for (int value : arr) {
    unique.add(value);
}

110. Character frequency.

Map<Character, Integer> frequency = new HashMap<>();

for (char c : str.toCharArray()) {
    frequency.put(c, frequency.getOrDefault(c, 0) + 1);
}

111. First non-repeating character.

Approach:

Count frequency
Iterate original string
Return first character with frequency 1

112. Check whether two strings are anagrams.

Frequency approach:

public static boolean isAnagram(String a, String b) {
    if (a.length() != b.length()) {
        return false;
    }

    int[] counts = new int[256];

    for (int i = 0; i < a.length(); i++) {
        counts[a.charAt(i)]++;
        counts[b.charAt(i)]--;
    }

    for (int count : counts) {
        if (count != 0) {
            return false;
        }
    }

    return true;
}

113. Reverse words in a sentence.

Input:

I love Java

Output:

Java love I

Example:

String[] words = sentence.trim().split("\\s+");
Collections.reverse(Arrays.asList(words));
String result = String.join(" ", words);

114. Find the missing number.

For values from 1 to n:

long expected = (long) n * (n + 1) / 2;
long actual = 0;

for (int value : arr) {
    actual += value;
}

return expected - actual;

115. Find common elements in two arrays.

Use a set for one array and check the second.

116. Implement binary search.

public static int binarySearch(int[] arr, int target) {
    int left = 0;
    int right = arr.length - 1;

    while (left <= right) {
        int mid = left + (right - left) / 2;

        if (arr[mid] == target) {
            return mid;
        }

        if (arr[mid] < target) {
            left = mid + 1;
        } else {
            right = mid - 1;
        }
    }

    return -1;
}

Time:

O(log n)

117. Sort without a library.

Bubble sort:

for (int i = 0; i < arr.length - 1; i++) {
    for (int j = 0; j < arr.length - i - 1; j++) {
        if (arr[j] > arr[j + 1]) {
            int temp = arr[j];
            arr[j] = arr[j + 1];
            arr[j + 1] = temp;
        }
    }
}

Time:

O(n²)

Know why better algorithms such as merge sort exist.

118. Longest substring without repeating characters.

Use a sliding window.

Key idea:

Expand right pointer
Track last seen position
Move left pointer when duplicates appear

Target time:

O(n)

119. Balanced brackets.

Use a stack.

Example:

{[()]}

valid.

{[(])}

invalid.

120. Two Sum.

public static int[] twoSum(int[] nums, int target) {
    Map<Integer, Integer> indexByValue = new HashMap<>();

    for (int i = 0; i < nums.length; i++) {
        int needed = target - nums[i];

        if (indexByValue.containsKey(needed)) {
            return new int[] { indexByValue.get(needed), i };
        }

        indexByValue.put(nums[i], i);
    }

    return new int[] {};
}

Expected time:

O(n)

TCS Software Engineering Interview Questions

121. What is SDLC?

Typical stages:

Requirements
Analysis
Design
Development
Testing
Deployment
Maintenance

In real organizations, these stages may overlap.

122. Agile vs Waterfall?

Waterfall

Sequential.

Works better when requirements are stable and predictable.

Agile

Iterative.

Useful where feedback and changing requirements matter.

123. What is Scrum?

Common Scrum concepts:

Product Owner
Scrum Master
Developers
Product backlog
Sprint backlog
Sprint
Daily Scrum
Review
Retrospective

124. What is version control?

Version control records code history and allows collaboration.

Benefits:

Audit history
Branching
Rollback
Parallel work
Code review

125. Merge vs rebase?

Merge

Preserves branch history and creates a merge commit where needed.

Rebase

Rewrites commits on top of another base.

Avoid rebasing shared history unless you understand the impact.

TCS Cloud, API and Microservices Interview Questions

126. What is cloud computing?

Cloud computing provides infrastructure and services on demand.

Examples:

Compute
Storage
Database
Networking
Messaging
Analytics
Monitoring

127. IaaS vs PaaS vs SaaS?

IaaS

Infrastructure.

Example concept:

Virtual machines.

PaaS

Managed application platform.

SaaS

Complete software delivered to end users.

128. What is REST?

REST is an architectural style commonly used for network APIs.

Common HTTP methods:

GET
POST
PUT
PATCH
DELETE

Good API design also considers:

Status codes
Validation
Idempotency
Pagination
Versioning
Error format

129. What is a microservice?

A microservice is a small, independently deployable service organized around a business capability.

Good microservices usually own:

Logic
Deployment lifecycle
Often their own data boundary

130. Monolith vs microservices?

Monolith advantages

Simpler deployment
Easier local debugging
Lower infrastructure complexity

Microservices advantages

Independent deployment
Independent scaling
Team autonomy

Microservices costs

Networking
Observability
Distributed transactions
Deployment complexity
Data consistency

131. What is an API gateway?

It can handle:

Routing
Authentication
Authorization
Rate limiting
Logging
Request transformation

132. What is load balancing?

Load balancing distributes requests across multiple instances.

Common algorithms include:

Round robin
Least connections
Weighted distribution

133. What is Docker?

Docker packages software into images and runs those images as containers.

A container includes:

Application
Runtime
Dependencies
Configuration references

134. Docker vs virtual machine?

Containers

Share host kernel.

VMs

Run guest operating systems on virtualized hardware.

Containers typically start faster and use fewer resources.

135. What is Kubernetes?

Kubernetes orchestrates containerized workloads.

Important concepts:

Pod
Deployment
ReplicaSet
Service
ConfigMap
Secret
Ingress
Namespace
Horizontal Pod Autoscaler

TCS Digital and Prime Interview Questions

136. Explain your strongest programming language deeply.

If Java is your strongest language, prepare:

JVM
Collections
Memory
Exceptions
Generics
Streams
Concurrency
OOP
Garbage collection

Do not describe yourself as "expert" unless you are ready for depth.

137. Design a URL shortener.

Start with requirements.

Functional

Create short URL
Redirect short URL
Optional expiration
Optional analytics

Non-functional

Low latency
High availability
Scalability

Components

Client
→ API
→ Short-code service
→ Database
→ Cache

Discuss:

Unique ID generation
Base62 encoding
Collisions
Cache
Database choice

138. How would you design a scalable application?

A strong answer starts with traffic and bottlenecks.

Possible architecture:

Users
→ CDN
→ Load Balancer
→ Stateless App Instances
→ Cache
→ Database
→ Queue / Workers

Discuss scaling only where necessary.

139. What happens when Java code runs?

Simplified:

.java
→ javac
→ bytecode
→ class loader
→ verification
→ JVM execution
→ interpretation/JIT compilation

140. What is concurrency?

Concurrency means multiple tasks can make progress over overlapping periods.

Parallelism means tasks literally execute at the same time on different cores.

They are related but not identical.

141. Why not index every column?

Because indexes:

Consume disk
Add write overhead
Increase maintenance
Can confuse planning if poorly designed
May not help low-selectivity queries

142. How would you debug a slow API?

A disciplined flow:

Measure latency
Identify whether slowness is consistent or intermittent
Check application metrics
Check logs
Inspect database query time
Check external dependencies
Check CPU/memory
Check thread pools and connection pools
Trace request path
Optimize the actual bottleneck

Do not immediately say "add caching."

143. How would you troubleshoot high CPU usage?

Potential causes:

Busy loops
Excessive requests
Serialization
Compression
Heavy regex
Inefficient algorithms
GC pressure
Thread contention

Useful tools:

CPU profiler
Thread dump
Metrics
Tracing

144. What is caching?

Caching stores frequently accessed data in a faster location.

Examples:

Browser cache
CDN
Redis
Application cache

Common challenge:

145. SQL vs NoSQL?

Do not choose based on fashion.

Ask:

Do I need transactions?
Are relationships important?
What are query patterns?
What scale?
What consistency model?
How flexible is the schema?

TCS Interview Questions for Experienced Candidates

146. Explain your current architecture.

Use the actual system.

A useful format:

Client
→ API Gateway
→ Services
→ Database
→ Cache
→ Queue
→ External Systems

Explain:

Traffic flow
Failure handling
Data ownership
Deployment
Monitoring

147. Describe a production incident.

Use:

Situation → Impact → Investigation → Root cause → Fix → Prevention

Example:

148. How do you handle API failures?

Important concepts:

Timeouts
Retry
Backoff
Circuit breaker
Idempotency
Fallback
Bulkhead
Monitoring

Never retry every error blindly.

149. How did you improve application performance?

Good answer:

Use real numbers only if they are accurate.

150. How do you secure REST APIs?

Discuss:

HTTPS
Authentication
Authorization
Token validation
Input validation
Rate limiting
Secrets management
Audit logs
Dependency updates
Principle of least privilege

151. How do microservices communicate?

Synchronous

REST
gRPC

Asynchronous

Kafka
RabbitMQ
Queue systems

Trade-off:

Synchronous calls are easier to reason about but create runtime dependencies.

Asynchronous messaging improves decoupling but adds eventual consistency and operational complexity.

152. What is a circuit breaker?

A circuit breaker protects a system from repeatedly calling an unhealthy dependency.

States often include:

Closed
Open
Half-open

153. What is idempotency?

If the same request is repeated, the final result should remain equivalent after the first successful application.

Critical for:

Payments
Order creation
Retries
Webhooks

154. What monitoring tools have you used?

Mention only actual experience.

Possible tools:

CloudWatch
Prometheus
Grafana
ELK
Splunk
Datadog
OpenTelemetry

Then explain what you monitored.

155. Why are you leaving your current company?

Focus on growth.

Example:

TCS Behavioral Interview Questions

156. Tell me about a conflict with a teammate.

Use STAR.

Situation

What happened?

Task

What did you need to achieve?

Action

What did you do?

Result

What happened afterward?

157. Tell me about a mistake.

Strong answers show ownership.

Example:

Do not blame someone else.

158. Describe a difficult deadline.

Explain prioritization.

Good answer includes:

Scope clarification
Critical path
Communication
Risk escalation
Delivery

159. Tell me about a time you demonstrated leadership.

Leadership can mean:

Taking ownership
Helping teammates
Coordinating work
Resolving uncertainty
Making a decision

160. Tell me about a failure.

Choose something real but not catastrophic.

Focus on the learning.

161. Tell me about a time you learned something quickly.

Use:

Need → Learning approach → Practice → Application → Result

162. How do you handle pressure?

A good answer:

163. How do you handle disagreement with a manager?

Show professionalism.

164. Tell me about a time you helped someone.

Use an example where your action had a meaningful result.

165. Tell me about changing requirements.

Discuss:

New requirement
Impact analysis
Reprioritization
Communication
Implementation

TCS Interview Questions for Java Developers

If your resume includes Java, interviewers may go beyond the general questions above.

Prepare these additional areas:

Java collections

Know:

List
Set
Map
ArrayList
LinkedList
HashSet
TreeSet
HashMap
TreeMap
ConcurrentHashMap

Java 8+

Prepare:

Lambda expressions
Streams
Optional
Functional interfaces
Method references

Concurrency

Prepare:

Thread
Runnable
ExecutorService
Future
CompletableFuture
synchronized
volatile
Atomic classes
Locks

JVM basics

Prepare:

Heap
Stack
Metaspace
Class loading
Garbage collection
JIT

Spring Boot candidates

Also prepare:

Dependency injection
Bean lifecycle
REST controllers
Validation
Exception handling
Spring Data JPA
Transactions
Profiles
Configuration
Security
Actuator

TCS Interview Questions for SQL and Database Roles

Be prepared to:

Write joins
Write subqueries
Use window functions
Explain indexes
Diagnose slow queries
Understand execution plans
Explain normalization
Discuss transaction isolation
Explain deadlocks
Explain constraints

Example advanced question

Why can a query still be slow even when an index exists?

Possible reasons:

Index is not selective
Query cannot use the index
Wrong column order in composite index
Function applied to indexed column
Outdated statistics
Large result set
Sorting/grouping cost
I/O bottleneck

TCS Interview Questions for Cloud Candidates

Prepare:

Regions
Availability zones
Virtual machines
Object storage
VPC/networking
IAM
Load balancers
Managed databases
Autoscaling
Monitoring
Backup and disaster recovery

If you mention AWS, be prepared for:

EC2
S3
RDS
IAM
VPC
CloudWatch
Route 53
Auto Scaling
ELB

TCS Interview Questions for Microservices Candidates

Prepare:

Service discovery
API gateway
Synchronous vs asynchronous communication
Circuit breakers
Distributed tracing
Centralized logging
Eventual consistency
Saga pattern
Idempotency
Retries
Timeouts
Configuration
Secrets
Docker
Kubernetes

How to Answer TCS Technical Questions When You Do Not Know the Answer

Do not invent.

A strong approach is:

Then explain what you know.

Example:

This is much better than bluffing.

How to Answer Coding Questions in a TCS Interview

Use this sequence.

1. Clarify the problem

Ask about:

Input size
Duplicate values
Empty input
Negative values
Expected output

2. Explain brute force

Show you understand the obvious solution.

3. Improve it

Discuss data structures or algorithms.

4. Write code

Keep it readable.

5. Test with examples

Use:

Normal case
Edge case
Empty/small case

6. State complexity

Always mention:

Time complexity
Space complexity

TCS Interview Preparation Plan: 7 Days

Day 1 — Resume + project

Prepare:

Tell me about yourself
Project architecture
Contributions
Challenges
Technologies

Day 2 — OOP + Java

Study:

OOP
Collections
Exceptions
Strings
HashMap
Threads

Day 3 — DBMS + SQL

Practice:

Joins
Grouping
Subqueries
Indexes
Transactions
Normalization

Day 4 — DSA

Practice:

Arrays
Strings
Stack
Queue
Hashing
Search
Sort

Day 5 — OS + networking

Review:

Process/thread
Memory
Deadlock
TCP/UDP
HTTP/HTTPS
DNS

Day 6 — Coding + role-specific topics

Practice 8–10 coding questions.

Then revise:

Spring Boot
Cloud
Microservices
DevOps
Frontend

depending on your role.

Day 7 — Mock interview

Do at least two complete mock interviews.

Record your answers if possible.

Look for:

Long pauses
Repetition
Weak explanations
Missing examples
Poor structure

TCS Interview Preparation Plan: 30 Days

If you have more time:

Week 1

Programming fundamentals + OOP.

Week 2

DBMS + SQL + OS + Networks.

Week 3

DSA + coding practice.

Week 4

Projects + HR + role-specific topics + mock interviews.

This is more effective than trying to study everything during the last weekend.

How AI Can Help With TCS Interview Preparation

AI can be useful for:

Generating mock questions
Reviewing your answers
Creating follow-up questions
Explaining technical concepts
Practicing behavioral responses
Simulating resume-based interviews

For a complete overview, read:

Interview Assistant: Complete Guide to AI-Powered Interview Support in 2026

A useful mock-interview prompt is:

Act as a TCS technical interviewer.

My target role is Java backend developer.
Ask one question at a time.
After every answer:
1. Evaluate technical correctness.
2. Ask one realistic follow-up question.
3. Increase difficulty gradually.
4. Include Java, SQL, Spring Boot, microservices, and project questions.

Practice TCS Interview Questions With InterviewAssist

You can also use InterviewAssist for permitted interview practice.

A useful workflow:

Upload your resume
Add the job description
Start a mock interview
Practice your introduction
Practice resume-based questions
Practice technical follow-ups
Review your weakest answers

Example sequence:

Then:

That is far more useful than memorizing isolated one-line definitions.

If cost is an important factor while comparing tools, see our guide to the cheapest AI interview assistants in 2026.

Comparing AI Interview Tools for TCS Preparation

InterviewAssist also has dedicated comparison guides for candidates evaluating interview-assistance platforms.

Chiku AI alternative

Read:

Best Chiku AI Alternative in 2026: InterviewAssist vs Chiku AI

Parakeet AI alternative

Read:

Best Parakeet AI Alternative in 2026

Also see:

What Is Parakeet AI? Complete Guide 2026

LockedIn AI alternative

Read:

Best LockedIn AI Alternatives in 2026

Final Round AI alternative

Read:

Best Final Round AI Alternatives in 2026

Use any interview-assistance tool only where permitted by the employer, interviewer, assessment provider, and applicable rules.

TCS Interview Preparation Checklist

Before your interview, make sure you can explain:

Tell me about yourself
Why TCS?
Why should we hire you?
Your final-year or current project
Your exact contribution
Your strongest programming language
OOP concepts
Collections
Exception handling
DBMS
SQL joins
Indexes
Transactions
Operating systems
Computer networks
Arrays
Strings
Hashing
Stack and queue
Searching
Sorting
Time complexity
Basic coding
Cloud basics
APIs
Microservices basics
Behavioral examples
Relocation
Career goals
Questions for the interviewer

Frequently Asked Questions About TCS Interviews

What questions are asked in a TCS interview?

TCS interviews can include questions from your resume, projects, programming language, OOP, DBMS, SQL, operating systems, networking, DSA, coding, APIs, cloud, microservices, and behavioral situations.

The actual mix depends on the role and hiring track.

How difficult is a TCS interview?

Difficulty varies by:

Hiring category
Role
Skill selected
Candidate experience
Interviewer
Earlier performance

A fresher interview may focus more on fundamentals and projects.

An experienced interview may go much deeper into architecture, production incidents, debugging, performance, and design decisions.

Is coding asked in TCS interviews?

Coding can be part of the selection process.

The current TCS NQT structure includes Advanced Coding in the Advanced section.

Software-development candidates should therefore practice coding rather than only theory.

What is the current TCS NQT duration?

TCS currently lists a total test duration of 190 minutes:

75 minutes Foundation
115 minutes Advanced

The current structure is published on the official TCS hiring page.

Is the Advanced section important for TCS Digital and Prime?

Yes.

TCS states that the Advanced section is mandatory for candidates aspiring for Digital or Prime offers.

Which programming language should I prepare?

Prepare the language you claim as your strongest.

Common choices include:

Java
Python
C
C++
JavaScript

Deep knowledge of one language is usually better than shallow knowledge of many.

How should freshers prepare?

Prioritize:

Resume
Academic project
Programming
OOP
DBMS
SQL
DSA
OS
Networks
HR questions

How should experienced candidates prepare?

Prepare:

Current architecture
APIs
Databases
Performance
Cloud
Security
Deployment
CI/CD
Monitoring
Incident handling
Design decisions
Leadership examples

What is the most important part of a TCS fresher interview?

There is no single guaranteed most important section, but your resume, project, programming fundamentals, and ability to explain concepts clearly are especially important preparation areas.

What if I cannot answer a technical question?

Do not guess wildly.

Say what you know.

Example:

Then give your best reasoned explanation.

How long should "Tell me about yourself" be?

Around 60–90 seconds is usually a useful target.

Long enough to show substance.

Short enough to remain focused.

Should I memorize HR answers?

No.

Prepare a structure and genuine examples.

Memorized answers often sound unnatural when the interviewer asks a slightly different question.

What questions should I ask at the end?

Examples:

What technologies does this role use most frequently?
What kind of projects would I initially work on?
What skills are most important for success in the team?
How is learning supported for new team members?

Final TCS Interview Tips for 2026

The biggest difference between weak and strong interview preparation is depth.

A weak candidate memorizes:

A stronger candidate understands:

Hashing
Buckets
hashCode()
equals()
Collisions
Load factor
Thread safety
ConcurrentHashMap

A weak candidate says:

A stronger candidate can explain:

Why PostgreSQL
Table design
Keys
Indexes
Query patterns
Transactions
Backups
Performance problems

A weak candidate says:

A stronger candidate can explain:

Why services were separated
How they communicate
How failures are handled
How requests are traced
How data consistency works
How services are deployed

That is the level of preparation you should aim for.

Start Practicing for Your TCS Interview

Use this guide as a structured question bank.

Do not try to memorize every sentence.

Instead:

Understand the concept
Explain it in your own words
Give a real example
Handle follow-up questions
Practice aloud

For additional preparation, explore:

You can also visit InterviewAssist to practice interview questions against your own resume and target role.

Prepare your fundamentals, know your project deeply, understand every skill on your resume, and practice explaining your reasoning clearly.