Verifone Front end Developer Interview Questions and Answers

Q1. Closures, setTimeout, Eventloop in javascript
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Q2. How to center a div in css3
Ans. 
To center a div in CSS3, use the 'margin: auto;' property along with a set width.
• Set the width of the div

• Use 'margin: auto;' to center the div horizontally

• Make sure the parent container has a defined width
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Q3. Call , bind and apply functions in javascript
Ans. 
call, bind, and apply are methods used to manipulate the context of a function in JavaScript.
• call() is used to invoke a function with a specified 'this' value and arguments provided individually.

• bind() is used to create a new function with a specified 'this' value and initial arguments.

• apply() is used to invoke a function with a specified 'this' value and arguments provided as an array.
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Round duration - 90 Minutes
Round difficulty - Easy

1 coding question which was quite easy. Some MCQ that includes basic questions related to html, css, javascript, oops, dbms and output.

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 a given capacity.
• Implement a doubly linked list to keep track of the order of keys based on their recent usage.

• Use a hashmap to store key-value pairs for quick access and updates.

• When capacity is reached, evict the least recently used item before inserting a new one.

• Update the order of keys in the linked list whenever a ke
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Round duration - 90 Minutes
Round difficulty - Easy

easy round. Had some frontend questions related to html ,css, js , etc Explain Closures in JavaScript. In how many ways can we specify the CSS styles for the HTML element?

Q1. 
String Palindrome Verification
Given a string, your task is to determine if it is a palindrome considering only alphanumeric characters.
Input:
The input is a single string without any leading or trailing...read more
Ans. 
Check if a given string is a palindrome considering only alphanumeric characters.
• Remove non-alphanumeric characters from the input string.

• Compare the string with its reverse to check for palindrome.

• Handle edge cases like empty string or single character input.

• Use two pointers approach for efficient comparison.
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Q2. DBMS Questions
normalization, indexing
Ans. 
Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity. Indexing is a technique to quickly retrieve data from a database.
• Normalization helps in reducing data redundancy by breaking down tables into smaller, related tables.

• Indexing is used to quickly retrieve data by creating indexes on columns in a table.

• Normalization ensures data integrity by minimizing data dupli...read more
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Round duration - 120 Minutes
Round difficulty - Hard

late at 8.00 pm

Q1. 
Priority CPU Scheduling Problem
Given 'N' processes with their “burst times”, where the “arrival time” for all processes is ‘0’, and the ‘priority’ of each process, your task is to compute the “waiting ti...read more
Ans. 
Implement Priority CPU Scheduling algorithm to compute waiting time and turn-around time for processes.
• Implement a function that takes in burst times, priorities, and number of processes as input

• Sort the processes based on priority, with lower process ID as tiebreaker

• Calculate waiting time and turn-around time for each process based on the scheduling algorithm
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Q2. Can you explain the concept of data spooling in operating systems?
Ans. 
Data spooling is a process where data is temporarily stored in a buffer before being sent to an output device.
• Data spooling helps in managing the flow of data between different devices by storing it temporarily.

• It allows for efficient processing of data by decoupling the input/output operations.

• Examples of data spooling include print spooling, where print jobs are stored in a queue before being sent to the printer.
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Q3. What is the difference between inheritance and generalization in the context of database management systems?
Ans. 
Inheritance is a relationship between a superclass and subclass, while generalization is a relationship between entities with common characteristics.
• Inheritance involves a parent-child relationship where the child class inherits attributes and methods from the parent class.

• Generalization involves grouping entities with common attributes into a higher-level entity.

• Inheritance is a specific form of generalization in obje...read more
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Round duration - 60 minutes
Round difficulty - Medium

test timing: 7-8 pm
2 programming questions
webcam proctored

Q1. 
Minimum Cost to Reach End Problem
You are provided with an array ARR of integers of size 'N' and an integer 'K'. The goal is to move from the starting index to the end of the array with the minimum possib...read more
Ans. 
Find minimum cost to reach end of array by jumping with constraints
• Use dynamic programming to keep track of minimum cost at each index

• Iterate through the array and update the minimum cost based on reachable indices within K steps

• Calculate cost to jump from current index to reachable indices and update minimum cost accordingly
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Palindrome String Validation
Determine if a given string 'S' is a palindrome, considering only alphanumeric characters and ignoring spaces and symbols.
Note:
The string 'S' should be evaluated in a case...read more
Ans. 
The task is to check whether a given string is a palindrome or not, considering only alphabets and numbers and ignoring symbols and whitespaces.
• Convert the string to lowercase and remove all symbols and whitespaces.

• Reverse the modified string and compare it with the original string.

• If they are equal, then the string is a palindrome.

• If not, then the string is not a palindrome.
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Q2. 
Square Root (Integral) Problem Statement
Given a number N, calculate its square root and output the integer part only.
Example:
Input:
18
Output:
4
Explanation:
The square root of 18 is approximate...read more
Ans. 
The task is to find the integral part of the square root of a given number.
• Use the built-in square root function to find the square root of the number.

• Convert the result to an integer by rounding down or using the floor function.

• Print the integer part of the square root as the output.
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Q3. 
Min Steps to One Using Dynamic Programming
Given a positive integer N, your task is to determine the minimum number of steps required to reduce N to 1.
Allowed Operations:
1) Subtract 1 from it: n = n -...read more
Ans. 
The task is to find the minimum number of steps required to reduce a positive integer to 1 using three given operations.
• Use dynamic programming to solve the problem efficiently.

• Create an array to store the minimum steps required for each number from 1 to N.

• Iterate from 2 to N and calculate the minimum steps for each number based on the three operations.

• Return the minimum steps for N.
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Round duration - 60 Minutes
Round difficulty - Medium

They started Fundamentals of OOP- Inheritance, Polymorphism

Q1. 
Maximum Subarray Sum Problem Statement
Given an array of integers, determine the maximum possible sum of any contiguous subarray within the array.
Example:
Input:
array = [34, -50, 42, 14, -5, 86]
Out...read more
Ans. 
The maximum sum of any contiguous subarray in an array is found using Kadane's algorithm in O(N) time.
• Initialize two variables, maxSum and currentSum, both set to the first element of the array.

• Iterate through the array from the second element.

• For each element, update currentSum by adding the element to it.

• If currentSum becomes negative, reset it to 0.

• If currentSum is greater than maxSum, update maxSum.

• After iterating ...read more
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Round duration - 30 Minutes
Round difficulty - Medium

Some people had two HR interviews but I only had one and interview went up till 11:30 pm and you get only 5-10 minutes to prepare for HR on Zoom