WatchGuard Technologies Sde1 Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Medium

The test was in the evening which was not too late. It was conducted on Hackerrank which is a very common platform and was hence familiar. There were 26 questions:
Q1: Coding Question
3 languages were allowed: c, java8, python3
Q2 - Q26: Multiple Choice Questions

Q1. 
Intersection of Linked List Problem
You are provided with two singly linked lists containing integers, where both lists converge at some node belonging to a third linked list.
Your task is to determine t...read more
Ans. 
Find the node where two linked lists merge, return -1 if no merging occurs.
• Traverse both lists to find the lengths and the last nodes

• Align the starting points of both lists by moving the longer list's pointer ahead by the difference in lengths

• Traverse both lists simultaneously until a common node is found, which is the merging point
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Round duration - 70 Minutes
Round difficulty - Medium

This was an Online Coding+MCQ round where we had a total of 50 MCQ questions and 1 coding problem. The coding problem was of easy to medium level but was a bit implementation heavy.

Q1. 
LRU Cache Design Question
Design a data structure for a Least Recently Used (LRU) cache that supports the following operations:
1. get(key) - Return the value of the key if it exists in the cache; otherw...read more
Ans. 
Design a Least Recently Used (LRU) cache data structure that supports get and put operations with capacity constraint.
• Implement a doubly linked list to maintain the order of recently used keys.

• Use a hashmap to store key-value pairs for quick access.

• When capacity is reached, evict the least recently used item before inserting a new item.

• Update the position of a key in the linked list whenever it is accessed or updated.

• H...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 1 coding question in which I was first required to explain my approach and then discuss the time and space complexities. After this , some basic questions from OOPS and Java were asked.

Q1. 
Detect and Remove Loop in Linked List
For a given singly linked list, identify if a loop exists and remove it, adjusting the linked list in place. Return the modified linked list.
Expected Complexity:
A...read more
Ans. 
Detect and remove loop in a singly linked list in place with O(n) time complexity and O(1) space complexity.
• Use Floyd's Cycle Detection Algorithm to identify the loop in the linked list.

• Once the loop is detected, use two pointers to find the start of the loop.

• Adjust the pointers to remove the loop and return the modified linked list.
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Q2. What is the difference between ArrayList and LinkedList in Java?
Ans. 
ArrayList is implemented using a dynamic array while LinkedList is implemented using a doubly linked list.
• ArrayList provides fast random access but slow insertion and deletion operations.

• LinkedList provides fast insertion and deletion operations but slow random access.

• Example: ArrayList is suitable for scenarios where frequent access and traversal of elements is required, while LinkedList is suitable for scenarios wher...read more
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Q3. What is the difference between abstraction and inheritance?
Ans. 
Abstraction focuses on hiding implementation details, while inheritance allows a class to inherit properties and behavior from another class.
• Abstraction is the concept of hiding the complex implementation details and showing only the necessary features of an object.

• Inheritance is a mechanism where a new class inherits properties and behavior from an existing class.

• Abstraction is achieved through interfaces and abstract...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round had questions from OS and OOPS. The interviewer also tested my problem solving skills by asking me some puzzles in the end.

Q1. Can you explain piping in Unix/Linux?
Ans. 
Piping in Unix/Linux allows the output of one command to be used as the input for another command.
• Piping is done using the | symbol

• Multiple commands can be piped together

• Piping allows for the creation of complex command chains

• Example: ls -l | grep txt
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Q2. What is a static variable in C?
Ans. 
A static variable in C is a variable that retains its value between function calls.
• Static variables are declared using the 'static' keyword.

• They are initialized only once and retain their value throughout the program's execution.

• Static variables have a default value of 0 if not explicitly initialized.

• They are stored in the data segment of the program's memory.

• Example: static int count = 0; declares a static variable 'c
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Q3. How can you measure exactly 4 liters of water using only a 3-liter can and a 5-liter can?
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The task was a Codility type

Q1. Data structures, Algorithm
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Basic question asked

Q1. Computer networking based question
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Q2. Dsa question based on graph and dp
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Q3. Based on operating system
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Q4. Function of oops
Ans. 
Object-oriented programming paradigm that focuses on objects and classes for code organization and reusability.
• Encapsulation: bundling data and methods that operate on the data into a single unit (object)

• Inheritance: ability of a class to inherit properties and behavior from another class

• Polymorphism: ability to present the same interface for different data types
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Q1. Behavior question asked
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Q1. There are lot of questions regarding networking
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Round duration - 60 Minutes
Round difficulty - Medium

This was an Online Coding+MCQ round where we had a total of 25 MCQ questions and 1 coding problem. The coding problem was of easy to medium level and anyone with a decent knowledge of DSA could pass the coding problem.

Q1. 
Rat In a Maze Problem Statement
Given a N * N maze with a rat placed at position MAZE[0][0], find and print all possible paths for the rat to reach its destination at MAZE[N-1][N-1]. The rat is allowed to...read more
Ans. 
Find all possible paths for a rat in a maze to reach its destination.
• Use backtracking to explore all possible paths in the maze.

• Mark visited cells and backtrack when reaching dead ends.

• Print the path when reaching the destination cell.

• Consider all possible movements: left, right, up, and down.

• Ensure the rat can only move through cells marked as 1.
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Round duration - 60 Minutes
Round difficulty - Medium

The interviewer asked 1 coding problem related to Dynamic Programming in this round and then the rest of the questions were preety much revolving around Computer Networks.

Q1. 
Ways To Make Coin Change
Given an infinite supply of coins of varying denominations, determine the total number of ways to make change for a specified value using these coins. If it's not possible to make...read more
Ans. 
The task is to find the total number of ways to make change for a specified value using given denominations.
• Use dynamic programming to solve this problem efficiently.

• Create a 1D array to store the number of ways to make change for each value from 0 to the target value.

• Iterate through the denominations and update the array based on the current denomination.

• The final answer will be the value at the target index of the ar
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Q2. What is the difference between IPv4 and IPv6?
Ans. 
IPv6 has a larger address space, improved security features, and better support for mobile devices compared to IPv4.
• IPv4 uses 32-bit addresses while IPv6 uses 128-bit addresses.

• IPv4 supports around 4.3 billion unique addresses, whereas IPv6 supports 340 undecillion unique addresses.

• IPv6 has built-in security features like IPsec, while IPv4 requires additional security protocols.

• IPv6 has better support for mobile device...read more
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Q3. Can you describe the OSI Reference Model?
Ans. 
The OSI Reference Model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven layers.
• The OSI Reference Model stands for Open Systems Interconnection Reference 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.

• The model help...read more
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Round duration - 60 minutes
Round difficulty - Medium

This round had 1 question related to Binary Tree Traversal followed by some core concepts related to Operating Systems. This round ended with the interviewer asking me the famous 2 wire burning puzzle.

Q1. 
Spiral Order Traversal of a Binary Tree
Given a binary tree with N nodes, your task is to output the Spiral Order traversal of the binary tree.
Input:
The input consists of a single line containing elem...read more
Ans. 
Implement a function to return the spiral order traversal of a binary tree.
• Traverse the binary tree in a spiral order, alternating between left to right and right to left at each level

• Use a queue to keep track of nodes at each level and a flag to switch direction

• Return the list of nodes in spiral order traversal
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Q2. What is memory protection in operating systems?
Ans. 
Memory protection in operating systems is a mechanism to prevent a process from accessing memory that has not been allocated to it.
• Memory protection prevents a process from accessing memory locations outside its allocated space.

• It helps in preventing one process from interfering with the memory of another process.

• Operating systems use techniques like virtual memory and access control lists to implement memory protectio...read more
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Q3. You have two wires of different lengths that take different times to burn. How can you measure a specific amount of time using these two wires?
Ans. 
Use two wires of different lengths to measure a specific amount of time by burning them simultaneously.
• Burn both wires at the same time, one wire will finish burning before the other

• Measure the time it takes for the first wire to burn completely

• Use this time as a reference to measure the specific amount of time by burning the second wire
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