QSS Technosoft Inc. Java Developer Interview Questions and Answers

Round duration - 50 minutes
Round difficulty - Medium

Round duration - 20 minutes
Round difficulty - Medium

Q1. 
Pair Sum Problem Statement
You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to find and return a list of all pairs of elements where each sum of a pair equals 'S'.
Note:
...read more
Ans. 
Given an array and a target sum, find pairs of elements that add up to the target sum.
• Iterate through the array and for each element, check if the complement (target sum - current element) exists in a hash set.

• If the complement exists, add the pair to the result list. Otherwise, add the current element to the hash set.

• Sort the pairs based on the first element and then the second element to meet the required output form
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Round duration - 20 minutes
Round difficulty - Easy

Round duration - 40 minutes
Round difficulty - Hard

Q1. Can you provide an example of how to use pointers in C/C++ and discuss different concepts related to them?
Ans. 
Pointers in C/C++ are variables that store memory addresses. They are used to manipulate memory directly and improve performance.
• Pointers are declared using an asterisk (*) before the variable name.

• Pointers can be used to dynamically allocate memory using functions like malloc() and free().

• Pointers can be used to pass variables by reference to functions.
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Q1. DS Algo, Backend and DB
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Q2. Stack(DS) question and DB based questions
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Q3. Scaling (Horizontal, Vertical) with use cases
Ans. 
Scaling refers to increasing capacity of a system. Horizontal scaling adds more machines, while vertical scaling adds more resources to a machine.
• Horizontal scaling involves adding more machines to a system to increase capacity

• Vertical scaling involves adding more resources to a machine to increase capacity

• Use cases for horizontal scaling include handling increased traffic or adding redundancy

• Use cases for vertical sca...read more
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Q1. Regarding the Past Projects, mine were with Firebase and Flutter.
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Q2. Medium DSA questions for Array and String and Flutter
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Q1. How make a queue using a stack
Ans. 
To implement a queue using a stack, use two stacks and simulate the queue operations.
• Use two stacks, one for enqueue operation and one for dequeue operation.

• For enqueue operation, simply push elements onto the stack used for enqueueing.

• For dequeue operation, if the dequeue stack is empty, pop all elements from enqueue stack and push onto dequeue stack.

• Then pop from the dequeue stack to simulate dequeue operation.
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Q2. Create a linked list
Ans. 
A linked list is a data structure consisting of nodes where each node points to the next node in the sequence.
• Create a Node class with data and next pointer

• Initialize a head pointer to null

• Add nodes by updating next pointers

• Traverse the list by following next pointers
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Easy to medium leetcode questions

Q1. Closures, hostings, react js, redux, hooks basic
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Q2. Html5, css3, basic javascript stuff
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Normal aptitude questions

Python basic and some basic coding questions

Advance level coding question

Round duration - 30 minutes
Round difficulty - Medium

It was in the morning around 9:00Am-9:30AM. Platform used for this round was hacerrank. Questions were of moderate to difficult level.

Q1. 
Count Subarrays with Given XOR Problem Statement
You are given an array of integers ARR and an integer X. Your task is to determine the number of subarrays of ARR whose bitwise XOR is equal to X.
Example...read more
Ans. 
Count the number of subarrays in an array whose XOR is equal to a given value.
• Iterate through the array and keep track of XOR values and their frequencies using a hashmap.

• For each element in the array, calculate the XOR value with all previous elements and check if it equals the given XOR value.

• Use the concept of XOR to efficiently solve the problem.

• Handle edge cases like XOR value being 0 separately.

• Time complexity ca...read more
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Q2. 
Distinct Characters Problem Statement
Given a string STR, return all possible non-empty subsequences with distinct characters. The order of the strings returned is not important.
Example:
Input:
STR = ...read more
Ans. 
Return all possible non-empty subsequences with distinct characters from a given string.
• Iterate through all possible subsequences of the input string

• Check for distinct characters in each subsequence

• Return the distinct character subsequences as an array of strings
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Round duration - 15 minutes
Round difficulty - Easy

It was in the night around 8:00PM-8:20PM. Interviewer was very calm in questioning. Platform used for this round was Skype and the questions focused more on personality rather than total.