Presto Infosolutions Software Developer Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Easy

Technical Interview round with questions on OOPS and OS mainly.

Q1. What are Little Endian and Big Endian in the context of computer architecture?
Ans. 
Little Endian and Big Endian refer to the order in which bytes are stored in computer memory.
• Little Endian stores the least significant byte first, while Big Endian stores the most significant byte first.

• Little Endian is commonly used in x86 architecture, while Big Endian is used in architectures like SPARC and PowerPC.

• Endianness can affect data transmission between systems with different byte orders.
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Q2. Write a program to determine if your system is little-endian or big-endian.
Ans. 
Program to determine system's endianness
• Check the endianness by storing a multi-byte integer and checking the byte order

• Use bitwise operations to extract the least significant byte

• If the least significant byte is at the lowest memory address, it's little-endian

• If the least significant byte is at the highest memory address, it's big-endian
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Q3. What is the volatile keyword in programming?
Ans. 
The volatile keyword in programming is used to indicate that a variable's value can be changed unexpectedly.
• Volatile keyword is used in multithreaded programming to prevent compiler optimizations on variables that can be changed by other threads.

• It tells the compiler not to cache the variable's value in a register, ensuring that every access is made to the variable's memory location.

• Commonly used in embedded systems pr...read more
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Q4. What is the use of a function pointer in C?
Ans. 
Function pointers in C are used to store the address of functions, allowing for dynamic function calls and callbacks.
• Function pointers can be used to implement callbacks in event-driven programming.

• They can be used to switch between different functions at runtime.

• Function pointers are commonly used in implementing data structures like function pointers in an array of function pointers.

• Example: void (*funcPtr)(int) = &a
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Q5. Design a data structure to implement multi-threading.
Ans. 
Design a data structure for multi-threading
• Use a thread-safe queue to manage tasks for each thread

• Implement a lock or semaphore to control access to shared resources

• Consider using condition variables for synchronization

• Use atomic operations for shared variables to prevent race conditions
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Q6. What does a kernel do?
Ans. 
The kernel is the core component of an operating system that manages system resources and provides a bridge between software and hardware.
• Manages system resources such as CPU, memory, and I/O devices

• Provides a bridge between software applications and hardware components

• Handles tasks such as process scheduling, memory management, and device drivers

• Controls communication between hardware and software layers
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Q7. What is a storage class in programming?
Ans. 
A storage class in programming defines the scope and lifetime of variables.
• Storage classes include auto, register, static, and extern.

• Auto variables are created when a function is called and destroyed when the function ends.

• Register variables are stored in CPU registers for faster access.

• Static variables retain their value between function calls.

• Extern variables are declared outside of any function and can be accessed
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Round duration - 30 minutes
Round difficulty - Easy

HR round with typical behavioral problems.

Round duration - 60 Minutes
Round difficulty - Medium

Timing: Morning
How was the environment? It happened in the Computer Lab of my institution
All students were assigned a computer and we had to solve questions on hackerrank

Q1. 
Order of People Heights Problem Statement
Consider 'N' individuals numbered from 0 to N-1 standing in a queue. You are provided with two arrays: Height and Infront, each consisting of 'N' non-negative int...read more
Ans. 
The task is to find the actual order of people in a queue based on their heights and the number of taller people in front of them.
• Iterate through the given arrays and create a list of tuples containing the height and number of taller people for each person.

• Sort the list of tuples in descending order of height and ascending order of the number of taller people.

• Create an empty result list and insert each tuple into the r...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Round was a mix of concepts from OOPS, OS and Problem Solving

Q1. 
Binary Search Tree Value Finder
Given a Binary Search Tree (BST) and a key value 'X', determine if there exists a node within the BST containing the value 'X'.
Example:
Input:
Consider the tree represe...read more
Ans. 
The task is to find if a given value is present in a Binary Search Tree (BST).
• Start from the root node and compare the value with the target value.

• If the value matches, return true.

• If the target value is less than the current node value, move to the left child.

• If the target value is greater than the current node value, move to the right child.

• Repeat the process until a match is found or a leaf node is reached.

• If a leaf...read more
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Q1. Check if the linked list is palindrome or not
Ans. 
To check if a linked list is a palindrome, compare the first half of the list with the reversed second half.
• Traverse the linked list to find the middle node

• Reverse the second half of the linked list

• Compare the first half with the reversed second half to check for palindrome
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Q2. C string questions
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Q1. Operating systems questions
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Q2. Linked list and system design question
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Q1. Linked list and double pointers
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Binary search and design a data-structure to do insert, delete and get random in O(1)

Questions regarding JS concepts. JS and React specific rounds, closures, Promises, etc

Q1. Solve a js problem to traverse a directory. Simple question
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Q1. Managerial round to understand roles and responsibilities in previous orgs.
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