Fiserv Full Stack Developer Interview Questions and Answers

It will be a basic maths questions.

As a general topic of trend in world.

To be known for programming knowledge about us.

Q1. Programming oridanited
Add your answer
Q2. Skill knowledge questions
Add your answer

Q1. Tell me about your self.
Add your answer
Q2. Family background .
Add your answer

Q1. System design interview
Add your answer

Q1. What is react and why are we using it
Ans. 
React is a JavaScript library for building user interfaces.
• React allows for building reusable UI components

• It uses a virtual DOM for efficient updates

• React is declarative, making it easier to reason about code

• It is widely used in web development for its performance and flexibility
Answered by AI
Add your answer
Q2. What is redux in react
Ans. 
Redux is a predictable state container for JavaScript apps.
• Redux is a state management library for React

• It helps in managing the state of the application in a predictable manner

• It follows a unidirectional data flow pattern

• It has three main components: store, actions, and reducers

• Store holds the state of the application

• Actions are plain JavaScript objects that describe what happened

• Reducers specify how the application's...read more
Answered by AI
Add your answer

Create a react app with redux

Round duration - 70 minutes
Round difficulty - Medium

There were 3 problems 1 was easy and 2 were of medium types.

Q1. 
Odd Even Levels in Binary Tree
Given a binary tree, the task is to compute the modulus of the difference between the sum of nodes at odd levels and the sum of nodes at even levels.
Input:
The first line...read more
Ans. DFS
1. Create two variables, one for storing the sum of nodes at the odd level and one for storing the sum of nodes at even level.
2. Use the below algorithm to calculate level sums where:
oddSum: denotes sum of nodes at odd levels, initially 0.
evenSum: denotes sum of nodes at ecen levels, initially 0.
level: the level of the current node, initially 1. 
void oddEvenLevelHelper(current, oddSum, evenSum, level)
 
• If the cur...read more
Answered Anonymously
Add your answer
Q2. 
Rotting Oranges Problem Statement
You are given a grid containing oranges where each cell of the grid can contain one of the three integer values:
• 0 - representing an empty cell
• 1 - representing a fre...read more
Ans. Naïve Solution
The idea is very simple and naive. We will process the rotten oranges second by second. Each second, we rot all the fresh oranges that are adjacent to the already rotten oranges. The time by which there are no rotten oranges left to process will be our minimum time.
 
In the first traversal of the grid, we will process all the cells with value 2 (rotten oranges). We will also mark their adjacent cells ...read more
Answered Anonymously
Add your answer

Round duration - 50 minutes
Round difficulty - Medium

the interviewer was very polite and straightforward, he didn't ask me to introduce myself and he directly jumps to the coding problems.
What is new about the relationship between the and tags in HTML5?
Explain Components, Modules and Services in Angular

Q1. 
Circular Move Problem Statement
You have a robot currently positioned at the origin (0, 0) on a two-dimensional grid, facing the north direction. You are given a sequence of moves in the form of a string ...read more
Ans. Optimal Approach
Initialize a variable ‘direction’ with 0 which means that the robot is initially facing towards the north.
direction: 0 -> Robot is facing towards the North
direction: 1 -> Robot is facing towards the West 
direction: 2 -> Robot is facing towards the South 
direction: 3 -> Robot is facing towards the West
 
Initialize two variables ‘x’ and ‘y’ as 0. They will represent the position ...read more
Answered Anonymously
Add your answer

Round duration - 70 minutes
Round difficulty - Easy

What is a View in sql? What are the TRUNCATE, DELETE and DROP statements?

Q1. 
Rotate Matrix by 90 Degrees Problem Statement
Given a square matrix 'MATRIX' of non-negative integers, rotate the matrix by 90 degrees in an anti-clockwise direction using only constant extra space.
Inpu...read more
Ans. Transpose and Reverse
The idea is to find the transpose of the given matrix and then reverse the columns of the transposed matrix. For example:
For the given 2D matrix:
	[ [ 1,  2,  3 ],
	  [ 4,  5,  6 ],
	  [ 7,  8,  9 ] ]
After taking transpose, it will become:
	[ [ 1,  4,  7 ],
	  [ 2,  5,  8 ],
	  [ 3,  6,  9 ] ]
After reversing the columns, it will ...read more
Answered Anonymously
Add your answer
Q2. 
Minimum Characters to Make a String Palindrome
Given a string STR of length N, determine the minimum number of characters to be added to the front of the string to make it a palindrome.
Input:
The first...read more
Ans. Brute Force
• The idea is pretty simple, as we can add only at the front, thus, we need to work on the prefix of the string.
• We need to find the largest prefix that is a palindrome. For example, in case of “abbac”, the largest prefix that is a palindrome is “abba”, now all you need to do is add the reverse of left out suffix i.e. “ca” at the front to make it a palindrome.
• This can be done in the following way:-
  • Until the str...read more
Answered Anonymously
Add your answer

Round duration - 20 minutes
Round difficulty - Easy

Round duration - 120 Minutes
Round difficulty - Medium

This was a coding round conducted from 12 PM to 2 PM and it was not proctored but we could not switch the tabs. There were 2 coding questions each of 100 marks. The MCQ had HTML,CSS, JS, SQL, Coding and aptitutude questions.

Q1. 
N Queens Problem
Given an integer N, find all possible placements of N queens on an N x N chessboard such that no two queens threaten each other.
Explanation:
A queen can attack another queen if they ar...read more
Ans. Backtracking
1. Instead of checking all the places on the chessboard, we can use backtracking and place queen row-wise or column-wise.
2. Suppose we place queens row-wise, and we start with the very first row. Place the queen and move to the next row until either there is a solution or there are no viable cells left.
3. As we backtrack, check to place the queen in the different columns of the same row.
4. When we can place a queen at ...read more
Answered Anonymously
Add your answer
Q2. 
Rearrange String Problem Statement
Given a string ‘S’, your task is to rearrange its characters so that no two adjacent characters are the same. If it's possible, return any such arrangement, otherwise re...read more
Ans. Brute force
In this approach, we will generate all the possible rearrangements of the string and check if the current string in our rearrangement does not have any two adjacent characters that are the same. If we can find any string which satisfies our criteria then we will return that string else we will return “not possible”.
 
We can implement the above approach by – 
1. Generate all permutations of a string.
2. For ...read more
Answered Anonymously
Add your answer

Round duration - 60 minutes
Round difficulty - Easy

There were two interviewers. They started by asking me to introduce myself and asked me to explain any one of my projects in my resume and after that, they asked me about the ML algorithms used in my project and about the difficulties faced. What is NaN property in JavaScript? This took around 10 minutes. They also asked 2 coding questions.
It was conducted at 10 AM on CodePair and MS Teams. Interviewers were friendly.

Q1. 
Group Anagrams Together
Given an array/list of strings STR_LIST, group the anagrams together and return each group as a list of strings. Each group must contain strings that are anagrams of each other.
E...read more
Ans. Sorting based Approach
The idea behind this approach is that two or more than two strings are anagrams if and only if their sorted strings are equal. So we will use a HashMap, let’s say “anagramGroup”, where each key is a sorted string, and the key will be mapping to the list of indices from the given list of strings that form a group of anagrams. This means that if we sort the strings at those indices, we will get the ...read more
Answered Anonymously
Add your answer
Q2. 
Friends Pairing Problem
The task is to determine the total number of ways to pair up 'N' friends or leave some of them single, following these rules:
1. Each friend can either pair with one other friend ...read more
Ans. Bruteforce
The idea is to solve the problem using recursion and break down the problem into different subproblems.
Let’s define NUMBER_OF_WAYS(N) as the total number of ways ‘N’ friends can be paired up or remain single.
The N-th person has two choices - either remain single or pair up with one of the other ‘N - 1’ friends.
If he remains single, then the number of possible pairings are NUMBER_OF_WAYS(N - 1) as there are (N...read more
Answered Anonymously
Add your answer

Round duration - 60 Minutes
Round difficulty - Medium

There were 2 questions based on data structures, the round started from 1.15 PM .Some SQL questions like What is a Subquery? What are its types? What are UNION, MINUS and INTERSECT commands?

Q1. 
Vertical Order Traversal Problem Statement
You are given a binary tree, and the task is to perform a vertical order traversal of the values of the nodes in the tree.
For a node at position ('X', 'Y'), th...read more
Ans. Efficient Approach
The intuition is to find the breadth of the tree first so that we can beforehand know the maximum horizontal distance and minimum horizontal distance of a node from the root node. We can use the absolute value of minimum horizontal distance as an offset. Now we can use an array/list visited to store the visited nodes where ith element will store the node at (i - offset”) distance horizontally from the...read more
Answered Anonymously
Add your answer
Q2. 
Divide Two Integers Problem Statement
You are given two integers dividend and divisor. Your task is to divide the integers without using multiplication, division, and modular operators. Return the quotien...read more
Ans. Using Subtraction
We can subtract the divisor from the dividend until the dividend is greater than the divisor. The quotient will be equal to the number of total subtractions performed.
 
Below is the detailed algorithm:
 
1. Store the ‘IS_DIVIDEND_NEGATIVE = false’ and ‘IS_DIVISOR_NEGATIVE = false’.
2. Check if the ‘DIVIDEND’ and ‘DIVISOR’ are positive or negative and update the values of ‘IS_DIVIDEND_NEGATIVE’ and ...read more
Answered Anonymously
Add your answer

Round duration - 30 Minutes
Round difficulty - Easy

The round was at 7.30 PM and I was asked to introduce myself and we had basic talk on where I live and my interests. I asked about the work culture and about the role at the end.

Q1. You are presented with a puzzle where there are n balloons, and your task is to burst the maximum number of balloons using an arrow. How would you approach solving this puzzle?
Ans. 
This was basically finding a maximum number of points in a line. I coded that but he wanted an improved solution. He told me to assume the positions of balloons in a matrix where 1 represents if the balloon is present and vice versa. Then I had to find which row or column or diagonal had the maximum number of 1’s. Later he asked me if I had some questions.
Answered Anonymously
Add your answer

3 coding questions

Round duration - 70 minutes
Round difficulty - Medium

The test started around 3 pm and was of 70 minutes. 3 coding questions were asked which were mainly on trees and number theory.

Q1. 
Factorial Calculation Problem Statement
Develop a program to compute the factorial of a given integer 'n'.
The factorial of a non-negative integer 'n', denoted as n!, is the product of all positive integ...read more
Ans. Using while() loop
• This can be done using an if-else-if ladder to check for negative,0, and positive numbers.
• If the input is a positive number use a while loop to multiply n with n-1, n-2…1 and get the desired output.
Space Complexity: O(1)Explanation: Time Complexity: O(1)Explanation:
Answered Anonymously
Add your answer
Q2. 
Next Greater Element Problem Statement
Given a list of integers of size N, your task is to determine the Next Greater Element (NGE) for every element. The Next Greater Element for an element X is the firs...read more
Ans. Brute Force
For every element in the array, we will run a loop on its right side. As soon as we find an element on its right side which is greater than it, we will break the loop, assign it as the NGE of this element, move forward, and do the same for the next element.
Space Complexity: O(1)Explanation:
O(1)
 
No extra space is used.
Time Complexity: O(n^2)Explanation:
O(N ^ 2),  Where N is the number of elements ...read more
Answered Anonymously
Add your answer
Q3. 
Ceil Value from BST Problem Statement
Given a Binary Search Tree (BST) and an integer, write a function to return the ceil value of a particular key in the BST.
The ceil of an integer is defined as the s...read more
Ans. Brute Force
We will traverse the Binary search tree from the root node till we find the node whose key value is given, and upon getting that, we return the ceil value of it.

 
The steps are as follows:  
• Initialize ‘ceilValue’ to store the ceil value to be returned.
• We run a while loop till the value of the node is not equal to NULL.
  • If the value of the node is equal to ‘X’’ then we return the node value.
  • If th...read more
Answered Anonymously
Add your answer

Round duration - 60 minutes
Round difficulty - Medium

Interviewer was very friendly and supportive. My interview happened on google meet. What is a View? What is Denormalization? Difference between “==” and “===” operators in js.

Q1. 
Sub Sort Problem Statement
You are given an integer array ARR. Determine the length of the shortest contiguous subarray which, when sorted in ascending order, results in the entire array being sorted in a...read more
Ans. Brute Force
In this approach, we consider every possible subarray that can be formed from the given array ‘ARR’. For every subarray ARR[i … j] considered, we need to check whether this is the smallest unsorted subarray or not.
 
The algorithm is as follows:
1. Let’s take the variable ‘ANS’ equal to 'N' (the length of the array) initially.
2. Now for every subarray ARR[i … j], we will find the maximum and minimum value lying ...read more
Answered Anonymously
Add your answer
Q2. 
Sort 0 1 2 Problem Statement
Given an integer array arr of size 'N' containing only 0s, 1s, and 2s, write an algorithm to sort the array.
Input:
The first line contains an integer 'T' representing the n...read more
Ans. Sorting
Use any good sorting algorithm like Merge Sort, Quick Sort or inbuilt sorting function of different languages.
• Sort the Array and just return.
Space Complexity: O(1)Explanation:
O(1), As we are using constant space.
Time Complexity: O(nlogn)Explanation:
O(N*log(N)), where ‘N’ is the size of the array.
We are using inbuilt sort algorithm which has Overall Time Complexity O(N*log(N))
Answered Anonymously
Add your answer

Round duration - 60 minutes
Round difficulty - Medium

What are some of the advantages of Angular over other frameworks?

Q1. 
Cousin Nodes in a Binary Tree
Determine if two nodes in a binary tree are cousins. Nodes are considered cousins if they are at the same level and have different parents.
Explanation:
In a binary tree, e...read more
Ans. Recursive Solution
• Find the levels of both the given nodes.
• This can be done by making a separate function for finding the level/by using level order traversal.
• The levels should be the same.
• Check if both the nodes are siblings or not.
• This can again be done by simply going through the entire Binary Tree and checking if the node’s children are the given two nodes. If this is true, then given two nodes are siblings and henc...read more
Answered Anonymously
Add your answer

Round duration - 10 minutes
Round difficulty - Easy

I got a call from HR in the evening around 6:30 pm.

Q1. Can you tell me about yourself?
Ans. 
Tip 1 : Do prepare such questions before hand only.
Tip 2 : Speak confidently.
Answered Anonymously
Add your answer
Q2. How was your experience with the previous two technical rounds?
Ans. 
Tip 1 : Do remember the names of the interviewers who took your interview.
Answered Anonymously
Add your answer
Q3. What do you know about Paytm?
Ans. 
Tip 1 : Do a research before hand about what does the company do.
Answered Anonymously
Add your answer