QUICK HEAL TECHNOLOGIES Security Engineer Interview Questions and Answers

Design a traffic signal system

• Identify the number of lanes and intersections

• Determine the traffic flow and peak hours

• Choose appropriate sensors and controllers

• Implement a synchronization algorithm

• Consider emergency vehicle prioritization

• Include pedestrian crossing signals

• Ensure compliance with local regulations

Hashmap is a data structure that stores key-value pairs and provides constant time complexity for insertion, deletion, and retrieval.

• Hashmap uses hashing function to map keys to indices in an array

• Collisions can occur when multiple keys map to the same index, which can be resolved using separate chaining or open addressing

• Java implementation: HashMap map = new HashMap<>();

Printing patterns using code

• Identify the pattern to be printed

• Use loops to print the pattern

• Adjust the loop variables to control the pattern

• Use conditional statements to modify the pattern

• Examples: printing stars, triangles, squares, etc.

Common point in linked list refers to the node where two or more linked lists intersect.

• The common point can be found by traversing both linked lists and comparing the nodes.

• The common point can also be found by using two pointers, one for each linked list, and moving them until they meet at the common point.

• Examples include finding the intersection point of two linked lists or finding the loop in a linked list.

A generic swap function swaps two values of any data type.

• The function should take two parameters of any data type.

• Use a temporary variable to store the value of one parameter.

• Assign the value of the second parameter to the first parameter.

• Assign the value of the temporary variable to the second parameter.

Search for an element in a rotated sorted linked list.

• Find the pivot point where the list is rotated.

• Divide the list into two sublists based on the pivot point.

• Perform binary search on the appropriate sublist.

• Handle edge cases such as empty list and list with only one element.

Search an element in a rotated sorted array

• Find the pivot point where the array is rotated

• Divide the array into two sub-arrays based on pivot point

• Perform binary search on the appropriate sub-array

• Repeat until element is found or sub-array size is 1

Find 5 missing numbers in an array of size 95 containing numbers in range 1 to 100.

• Create a boolean array of size 100 and mark the present numbers

• Iterate through the boolean array and find the missing numbers

• Alternatively, use a HashSet to store the present numbers and find the missing ones

Given a Sudoku board, find possible numbers for an empty cell.

• Iterate through empty cells and check possible numbers using row, column, and box constraints.

• Use a set to keep track of possible numbers for each empty cell.

• Return the set of possible numbers for the given empty cell.

Find integer average of 4 unsigned integers without typecasting

• Add all the integers and divide by 4

• Use bit shifting to divide by 4

• Handle overflow by using long long data type

• Use unsigned int data type for input

Code to identify 32 bit or 64 bit architecture of a processor

• Check if the operating system is 32 bit or 64 bit

• If OS is 32 bit, processor is 32 bit

• If OS is 64 bit, check if processor supports 64 bit architecture

• Use CPUID instruction to check if processor supports 64 bit architecture

Convert binary number to base 64 integer

• Divide the binary number into groups of 6 bits

• Convert each group of 6 bits to decimal

• Map the decimal value to the corresponding base 64 character

• Concatenate the base 64 characters to form the final integer

Find median of 2 sorted arrays in O(log N) time complexity and O(1) space complexity

• Use binary search to find the partition point in both arrays

• Calculate the median based on the partition point and array sizes

• Adjust the partition points based on the median value

• Repeat until the partition points are at the median

• Handle edge cases such as empty arrays and uneven array sizes

Anagram of strings in O(1) space complexity

• Use a fixed size array of integers to store the frequency of characters in the first string

• Iterate through the second string and decrement the frequency of each character in the array

• If all the frequencies are zero, then the strings are anagrams

• Return true or false accordingly

Level order traversal of a tree using Queue

• Create a queue and add the root node to it

• While the queue is not empty, remove the front node and print its value

• Add the left and right child nodes of the removed node to the queue

• Repeat until the queue is empty

Reverse level order traversal of a tree using Queue

• Create a queue and push the root node into it

• While the queue is not empty, pop the front node and push its children into the queue

• Add the popped node to a stack

• Once the queue is empty, pop elements from the stack and print them

BFS and DFS are graph traversal algorithms. BFS explores nodes level by level while DFS explores nodes depth by depth.

• BFS uses a queue while DFS uses a stack or recursion.

• BFS is optimal for finding shortest path while DFS is optimal for finding a path between two nodes.

• BFS requires more memory as it stores all the nodes at each level while DFS requires less memory.

• BFS can be used to find connected components while DFS

Find product of each element of an array except that element in O(N) time complexity without using / operation

• Use prefix and suffix products

• Multiply prefix and suffix products for each element to get the final product

• Handle edge cases where array has 0 or 1 element separately

Recursively delete a linked list

• Create a recursive function that takes the head of the linked list as input

• Base case: if the head is null, return

• Recursively call the function with the next node as input

• Delete the current node

Recursively delete a linked list from the end.

• Start from the head and recursively traverse to the end of the list.

• Delete the last node and set the second last node's next pointer to null.

• Repeat until the entire list is deleted.

• Use a recursive function to implement the deletion process.

Recursively delete a tree by deleting all its child nodes and then the parent node.

• Start from the leaf nodes and delete them first.

• Then move up to the parent nodes and delete them.

• Repeat until the root node is deleted.

• Use post-order traversal to ensure child nodes are deleted before parent nodes.

Recursively delete elements from the end of an array.

• Create a recursive function that removes the last element of the array.

• Call the function recursively until the desired number of elements are removed.

• Handle edge cases such as empty arrays and removing more elements than the array contains.

Floyd Warshall finds shortest path between all pairs of vertices while Djikstra finds shortest path from a single source.

• Floyd Warshall is used for dense graphs while Djikstra is used for sparse graphs.

• Floyd Warshall has a time complexity of O(n^3) while Djikstra has a time complexity of O((n+m)logn).

• Floyd Warshall can handle negative edge weights while Djikstra cannot.

• Floyd Warshall can detect negative cycles while Dj

There is no known algorithm to find shortest path in 2-D space in O(log N) time.

• The best known algorithm for finding shortest path in 2-D space is Dijkstra's algorithm which has a time complexity of O(N^2).

• Other algorithms like A* and Bellman-Ford have better time complexity but still not O(log N).

• If the points are on a grid, Lee algorithm can be used which has a time complexity of O(N).

Design a system for putting newspapers using classes and functions

• Create a Newspaper class with attributes like title, date, and content

• Create a Publisher class with methods to publish and distribute newspapers

• Create a Subscriber class with methods to subscribe and receive newspapers

• Use inheritance to create different types of newspapers like daily, weekly, etc.

• Implement a database to store newspaper information and ha

I believe practical experience is more valuable than higher studies.

• I have gained valuable experience through internships and projects.

• I prefer hands-on learning and problem-solving over theoretical knowledge.

• I am constantly learning and improving my skills through online courses and workshops.