PKF International Interview Questions and Answers

Round duration - 40 minutes
Round difficulty - Medium

The test has 3 sections :
1. Quantitative contains 20 questions. These questions are easy to me. If u practice quant, you can easily solve it.

2. Technical contains 20 questions. Some questions are on C , C++ , java outputs. Remaining are based on DSA. If u Know all the time complexities of algorithms then it is easy . In technical they gave one DSA problem.
 

3. Essay: They have given one picture and then asked to write an essay by seeing the picture.

Q1. 
Dijkstra's Algorithm for Shortest Path
Given an undirected graph with 'V' vertices labeled from 0 to V-1 and 'E' edges. Each edge has a weight that represents the distance between two nodes 'X' and 'Y'.
...read more
Ans. 
Dijkstra's algorithm is used to find the shortest path distances from a source node to all other vertices in a graph.
• Dijkstra's algorithm is a greedy algorithm that finds the shortest path from a source node to all other nodes in a graph.

• It uses a priority queue to select the node with the smallest distance and relaxes its neighbors.

• The algorithm maintains a distance array to keep track of the shortest distances from t...read more
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Round duration - 60 minutes
Round difficulty - Easy

3 persons are there in panel. They are asking questions on basic concepts in subjects and some advanced concepts.

Q1. What is a Daemon Process?
Ans. 
A daemon process is a background process that runs continuously to perform system tasks.
• Daemon processes do not have a controlling terminal.

• They typically run in the background and perform tasks such as managing hardware devices, network services, or system maintenance.

• Examples of daemon processes include cron, sshd, and apache.

• Daemon processes are often started during system boot and run until the system is shut down.
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Q2. What are the advantages of system calls in operating systems?
Ans. 
System calls provide a way for user-level processes to interact with the operating system kernel.
• System calls allow user programs to request services from the operating system.

• They provide a secure and controlled way for applications to access system resources.

• System calls enable processes to perform tasks such as file operations, network communication, and process management.

• Examples of system calls include open(), re
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Q3. Can you explain the select() system call?
Ans. 
The select() system call is used in Unix-like operating systems to monitor multiple file descriptors for activity.
• select() allows a program to wait for multiple I/O operations to complete on multiple file descriptors.

• It takes three sets of file descriptors as arguments - readfds, writefds, and errorfds.

• The function will block until an activity is detected on one of the file descriptors or until a timeout occurs.

• select(...read more
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Round duration - 45 minutes
Round difficulty - Medium

Technical Interview round with questions on DSA.

Q1. 
Binary Tree Mirror Conversion Problem
Given a binary tree, your task is to convert it into its mirror tree.
A binary tree is a data structure where each parent node has at most two children.
The mirror ...read more
Ans. 
Convert a binary tree into its mirror tree by interchanging left and right children of non-leaf nodes.
• Traverse the binary tree in postorder fashion and swap the left and right children of each non-leaf node.

• Use recursion to solve the problem efficiently.

• Remember to handle null child nodes represented by -1 in the input.
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Q2. 
Maximum Sum Subarray Problem Statement
Given an array of integers, find the maximum sum of any contiguous subarray within the array.
Example:
Input:
array = [34, -50, 42, 14, -5, 86]
Output:
137
Exp...read more
Ans. 
Find the maximum sum of any contiguous subarray within an array in O(N) time complexity.
• Iterate through the array and keep track of the maximum sum of subarrays encountered so far

• At each index, decide whether to include the current element in the subarray or start a new subarray

• Update the maximum sum if a new maximum is found

• Example: For array [34, -50, 42, 14, -5, 86], the maximum sum subarray is [42, 14, -5, 86] with
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Round duration - 45 minutes
Round difficulty - Hard

Technical Interview round with questions on DSA.

Q1. 
Find the Largest BST Subtree in a Given Binary Tree
Your task is to determine the size of the largest subtree of a given binary tree which is also a Binary Search Tree (BST).
BST Definition:
• The left...read more
Ans. 
Find the size of the largest subtree in a binary tree that is also a Binary Search Tree (BST).
• Traverse the binary tree in a bottom-up manner to check if each subtree is a BST.

• Keep track of the size of the largest BST subtree encountered so far.

• Use the properties of a BST to determine if a subtree is a valid BST.

• Consider edge cases such as empty tree or single node tree.

• Example: For input 1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1
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Q2. 
Next Higher and Previous Lower Number with Same Number of Set Bits
Given a positive integer n, the task is to find the next smallest integer and the previous largest integer that contain the exact same nu...read more
Ans. 
Find next smallest and previous largest integers with same number of set bits as given integer.
• Count the number of set bits in the given integer using bitwise operations.

• For next smallest integer, find the next number with same number of set bits by iterating through numbers greater than the given integer.

• For previous largest integer, find the previous number with same number of set bits by iterating through numbers sm
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