Techdefence Interview Questions, Process, and Tips

Round duration - 65 minutes
Round difficulty - Easy

There were 2 sections – 
Aptitude and Logical Reasoning and MCQ based on Java question ,C++, coding for 20 min and 45 min respectively.
Section A- Not very difficult to clear this round although less time was a problem.
Section B- It contains 15 multiple choice question on c/c++,java and 4 simple coding questions

Q1. 
Cycle Detection in a Singly Linked List
Determine if a given singly linked list of integers forms a cycle or not.
A cycle in a linked list occurs when a node's next points back to a previous node in the ...read more
Ans. 
Detect if a singly linked list forms a cycle by checking if a node's next pointer points back to a previous node.
• Traverse the linked list using two pointers, one moving at double the speed of the other.

• If the two pointers meet at any point, there is a cycle in the linked list.

• Use Floyd's Cycle Detection Algorithm for O(N) time complexity and O(1) space complexity.
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Round duration - 75 minutes
Round difficulty - Medium

It was an online coding test in which 3 coding question were given.

Q1. 
Smallest Window Problem Statement
Given two strings, S and X, your task is to find the smallest substring in S that contains all the characters present in X.
Example:
Input:
S = "abdd", X = "bd"
Outpu...read more
Ans. 
Find the smallest substring in string S that contains all characters in string X.
• Iterate through string S and keep track of characters in X found in a window

• Use two pointers to maintain the window and slide it to find the smallest window

• Return the smallest window containing all characters in X
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Q2. 
Smallest Integer Not Representable as Subset Sum
Given a non-decreasing sorted array ARR of N positive numbers, determine the smallest positive integer that cannot be expressed as the sum of elements from...read more
Ans. 
Find the smallest positive integer that cannot be expressed as the sum of elements from any proper subset of a non-decreasing sorted array of positive numbers.
• Start with the smallest possible integer that cannot be represented, which is 1.

• Iterate through the array and update the smallest integer that cannot be represented.

• If the current element is greater than the smallest integer that cannot be represented, return tha...read more
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Q3. 
Minimum Steps for a Knight to Reach Target
Given a square chessboard of size 'N x N', determine the minimum number of moves a Knight requires to reach a specified target position from its initial position...read more
Ans. 
Calculate the minimum number of moves a Knight needs to reach a target position on a chessboard.
• Implement a function that takes knight's starting position, target position, and chessboard size as input

• Use breadth-first search algorithm to find the shortest path for the Knight

• Consider all possible 8 movements of the Knight on the chessboard

• Return the minimum number of moves required for the Knight to reach the target po
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Round duration - 60 minutes
Round difficulty - Easy

It started with a discussion on the programs given in coding round. They asked me about my interest field after that they directly jumped into Networking, Linux and Ethical Hacking part looking my interest domain. They asked me various question on networking and linux.
Then they asked me to code a simple c program

Q1. 
Reverse Linked List Problem Statement
Given a singly linked list of integers, return the head of the reversed linked list.
Example:
Initial linked list: 1 -> 2 -> 3 -> 4 -> NULL
Reversed link...read more
Ans. 
Reverse a singly linked list of integers and return the head of the reversed linked list.
• Iterate through the linked list and reverse the pointers to point to the previous node.

• Keep track of the current, previous, and next nodes while reversing the linked list.

• Update the head of the reversed linked list as the last node encountered during reversal.
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Q2. What are the port numbers of protocols such as FTP and SMTP?
Ans. 
FTP uses port number 21 and SMTP uses port number 25.
• FTP uses port 21 for data transfer and port 20 for control information.

• SMTP uses port 25 for email communication.

• Understanding port numbers is important for network communication.
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Q3. Can you explain the OSI Model?
Ans. 
The OSI Model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven layers.
• The OSI Model stands for Open Systems Interconnection Model.

• It consists of seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

• Each layer has specific functions and communicates with the adjacent layers.

• Example: Layer 1 (Physical) deals with physi...read more
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Q4. How do you copy files in Linux?
Ans. 
To copy files in Linux, you can use the 'cp' command.
• Use the 'cp' command followed by the source file and destination directory to copy a file.

• To copy a directory and its contents, use the '-r' flag with the 'cp' command.

• You can also use wildcards like '*' to copy multiple files at once.
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