Photomath SDE-2 Interview Questions and Answers

Round duration - 30 minutes
Round difficulty - Medium

It was in the morning about 10:00AM-10:40AM. The platform used for this round was hackerrank. There are 15 MCQ's which cover portions of Aptitude, Data Structures, DBMS, SQL

Q1. Minimum Operations
You are given an array 'ARR' of 'N' positive integers. You need to find the minimum number of operations needed to make all elements of the array equal. You can perform a...read more
Ans. Brute Force
For making all elements equal you can select a target value and then you can make all elements equal to that. Now, for converting a single element to a target value you can perform a single operation only once. In this manner, you can achieve your task in the maximum of  ‘N’ operations but you have to minimize this number of operations and for this, your selection of target is very important because if ...read more
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Round duration - 15 minutes
Round difficulty - Easy

It was in the night around 7:00PM-7:20PM. Platform used for this round was skype. Interviewer was very serious while taking my interview.

Round duration - 60 minutes
Round difficulty - Easy

It is online round and it was conducted around 11 AM on campus. Difficulty was medium. 2 coding questions were asked. One question is based on arrays(easy) and the other question is based on usage of oops concepts like Inheritance, polymorphism. Everything went smooth.

Q1. Subarray With Given Sum
Given an array ARR of N integers and an integer S. The task is to find whether there exists a subarray(positive length) of the given array such that the sum of elements of the subar...read more
Ans. 
I started with brute force method but test cases were failed due to time complexity. Use a similar approach to a sliding window. Start with an empty subarray, add elements to the subarray until the sum is less than x. If the sum is greater than x, remove elements from the start of the current subarray
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Round duration - 50 minutes
Round difficulty - Medium

Round started with self introduction and discussion of project. Everything went fine.
Note: we didn't have hr round due to time constraint. You can expect hr round.

Q1. Find Duplicate
You have been given an integer array/list(ARR) of size N which contains numbers from 0 to (N - 2). Each number is present at least once. That is, if N = 5, the array/list constitutes values ...read more
Ans. 
Step 1: create an array of fixed size 256 as 256 ascii characters are available. Initialise all the elements of array with 0.
Step 2: iterate over array and store the frequency of every character.
Step 3: Iterate over the array and print the characters with frequency more than 1.
Note: problem can be solved using maps too.
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Q2. DBMS Questions
Explain the concept of normalisation and types.
Ans. 
Tip 1 : Explain everything clearly.
Tip 2 : Don't use the words that you are not confident about. Interviewer might ask questions based on your answers.
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Q3. DBMS Question
Explain ACID properties
Ans. 
Tip 1 : Go through DBMS concepts thoroughly.
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Q4. OOPS Question
Explain oops concepts with real life examples.
Ans. 
Tip 1 : Go through oops concepts thoroughly
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Round duration - 30 minutes
Round difficulty - Medium

Q1. Remove Duplicates
Given a string S, remove consecutive duplicates from it recursively.
Input Format :
String S
Output Format :
Output string
Constraints :
1 <= |S| <= 10^3
where |S| represen...read more
Ans. 
use the LinkedHashSet (Set Interface) to retain the original insertion order of the elements into the set.

The main factor that we must keep in mind when dealing with arrays is not the elements that have duplicates. The main problem here is removing the duplicates instead. Arrays are static data structures that are of fixed length, thus not possible to be altered. So, to delete elements from arrays, you need to create n...read more
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Round duration - 90 minutes
Round difficulty - Easy

Q1. Reverse String
You are given a string ‘S’. You are also given ‘M’ integers in an array ‘A’. You perform ‘M’ operations on this string. The operations are given in an array ‘A’ of size ‘M’.
You perform th...read more
Ans. 
Declare a string.
Take out the length of that string.
Loop through the characters of the string.
Add the characters in reverse order in the new string.
String str = "hello";

String reverse = "";

int length = str.length();

for (int i = 0; i < length; i++) {

reverse = str.charAt(i) + reverse;

}

System.out.println(reverse);
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Round duration - 50 minutes
Round difficulty - Medium

Amazon Online assessment which consisted of 2 coding DSA medium question

Q1. Question related to TreeMap
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Q2. Question related BFS
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Q3. System Design - Design Feed system
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Round duration - 360 minutes
Round difficulty - Hard

Timing- Any 6 hours of my choice in the 24 hour window. (10:00 p.m. to 4:00 a.m. I selected)
Environment was very friendly and easy to use.
No significant activity.
This was the only coding round.

Q1. Prime time again
You have been given two integers ‘DAY_HOURS’ and ‘PARTS’. Where ‘DAY_HOURS’ is the number of hours in a day and a day can be divided into ‘PARTS’ equal parts. Your task is to find total i...read more
Ans. 
Step1:First we had to decide whether the user enters valid parts which can occur in a day according to our question.
Step 2:Search for the prime time and valid times which can occur in the clock for the given range.
Step 3: Print the next valid time otherwise print 0.
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Round duration - 10-15 minutes
Round difficulty - Easy

Timing- 12:15 p.m. 
Environment was very good .
Not any significant activity.
The interviewer was very friendly and talked like friends.

Round duration - 20 minutes
Round difficulty - Medium

Timing- 12:30 p.m. to 12:45 p.m
Environment was very comfortable.
No other significant activity.
Interviewer was very good and talking very politely & friendly.

Round duration - 180 minutes
Round difficulty - Hard

Timing: 8 a.m. to 11a.m.
Environment was optimum.
No significant activity.

Q1. Edit Distance
You are given two strings 'S' and 'T' of lengths 'N' and 'M' respectively. Find the "Edit Distance" between the strings.
Edit Distance of two strin...read more
Ans. Recursive Approach
• We will write a recursive approach.
• The base case would be if the length of the first string is 0 then we need to add all the characters of the second string to the first string hence return the length of the second string. Similarly, if the length of the second string is 0 return length of the first string.
• Now the recurrence relation is as follows:
  • If the last characters of two strings are not the same...read more
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Round duration - 30 minutes
Round difficulty - Medium

Timing: 12:00 p.m. to 12:30 p.m.
The environment was quite good.
No significant activity.
Interviewers were very friendly. They were behaving like friends.

Round duration - 15 minutes
Round difficulty - Easy

Timing: 3:00 p.m. to 3:20 p.m.
Environment was very good.
No significant activity was monitored.
HR was very good and friendly.