Adc India Communications Java Developer Interview Questions and Answers

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...read more
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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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Round duration - 60 Minutes
Round difficulty - Easy

This was the initial round consisting of some aptitude questions,technical multiple choice questions and one coding question.
The Multiple Choice Questions were pretty straight forward.

Q1. 
Snake and Ladder Problem Statement
Given a 'Snake and Ladder' board with N rows and N columns, where positions are numbered from 1 to (N*N) starting from the bottom left, alternating direction each row, f...read more
Ans. 
Find the minimum number of dice throws required to reach the last cell on a 'Snake and Ladder' board.
• Start from the bottom left cell and move according to dice outcomes (1-6).

• Utilize snakes and ladders to reach the last cell faster.

• Keep track of the minimum number of throws required to reach the last cell.

• If unreachable, return -1 as output.
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Round duration - 45 Minutes
Round difficulty - Medium

I had two interviewers in this round.Some Problem solving questions were asked in this round.

Q1. 
Anagram Pairs Verification Problem
Your task is to determine if two given strings are anagrams of each other. Two strings are considered anagrams if you can rearrange the letters of one string to form the...read more
Ans. 
Check if two strings are anagrams of each other by comparing their sorted characters.
• Sort the characters of both strings and compare them.

• Use a dictionary to count the frequency of characters in each string and compare the dictionaries.

• Ensure both strings have the same length before proceeding with comparison.

• Example: For input 'spar' and 'rasp', after sorting both strings, they become 'aprs' which are equal, so return...read more
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Q2. Can you explain all the main Object Oriented Programming concepts?
Ans. 
Object Oriented Programming concepts include encapsulation, inheritance, polymorphism, and abstraction.
• Encapsulation: Bundling data and methods that operate on the data into a single unit (class). Example: Class Car with properties like color and methods like drive().

• Inheritance: Creating new classes based on existing classes, inheriting their attributes and methods. Example: Class SUV inheriting from class Car.

• Polymor...read more
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Q3. Can you explain one of your projects?
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Round duration - 45 Minutes
Round difficulty - Easy

Number Of Interviewers : 2
I was asked two problem solving questions and I was asked to explain my projects.

Round duration - 60 Minutes
Round difficulty - Easy

It was in the morning. Because of covid test was from home. We had 50 MCQ and 1 coding question. The coding question was pretty easy. MCQ were mixed, we even had questions from machine learning.

Q1. 
Maximum Path Sum Between Two Leaves
Given a non-empty binary tree where each node has a non-negative integer value, determine the maximum possible sum of the path between any two leaves of the given tree.
...read more
Ans. 
Find the maximum path sum between two leaf nodes in a binary tree.
• Traverse the tree to find the maximum path sum between two leaf nodes

• Consider both cases where the path passes through the root and where it doesn't

• Keep track of the maximum sum while traversing the tree
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Round duration - 60 minutes
Round difficulty - Medium

Interview round. Questions were based on projects, database and one coding question

Q1. 
Longest Subarray Zero Sum Problem Statement
Given an array of integers arr, determine the length of the longest contiguous subarray that sums to zero.
Input:
N (an integer, the length of the array)
arr (...read more
Ans. 
Find the length of the longest contiguous subarray that sums to zero in an array of integers.
• Use a hashmap to store the cumulative sum and its corresponding index.

• Iterate through the array, updating the sum and checking if the current sum exists in the hashmap.

• If the sum exists in the hashmap, update the maximum length of subarray with sum zero.

• Return the maximum length of subarray with sum zero.
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Round duration - 40 minutes
Round difficulty - Easy

Managerial round. Was asked questions on projects and management

Round duration - 10 minutes
Round difficulty - Easy

HR just asked about basic stuffs and all. Nothing technical

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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Level of difficult is medium

Focused more on arrays

There were 3 sections. 1st was aptitute 10 questions and 2nd section was technical 10 questions then 3rd section had 3 coding questions which were of easy level.

Q1. Questions related to OS and CN and Core java were asked.
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Q2. A coding question was also asked to to find the second largest number.
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Java code on their platform 2 codes I have to do