Polaris Java Developer Interview Questions and Answers

Normal DP question (LC med)

Q1. About Core Java
Add your answer
Q2. What is JVM & JRE
Ans. 
JVM stands for Java Virtual Machine, which is responsible for running Java programs. JRE stands for Java Runtime Environment, which includes JVM along with libraries and other components necessary for running Java applications.
• JVM is an abstract machine that provides a runtime environment in which Java bytecode can be executed.

• JRE includes JVM, libraries, and other files necessary for running Java applications.

• JVM is p...read more
Answered by AI
Add your answer

Q1. Date of Joining
Add your answer
Q2. When will you able to Join!
Add your answer

Q1. SELL ABD BUY 1 array question(easy level)
Ans. 
This question involves buying and selling items in an array.
• The array must contain strings.

• You need to implement a function to buy and sell items from the array.

• Provide examples of buying and selling operations.
Answered by AI
Add your answer

Round duration - 120 minutes
Round difficulty - Hard

There was 2 parts. First part problems were based on Quantitative Aptitude. Problems were of 3 types- Easy, Medium and Hard with different scores. Difficulty keeps on increasing if you answer correctly and keeps on decreasing if you answer incorrectly.
First part was of 45 mins.
Second part consisted of 2 coding problems- Medium, Hard. One was based on Greedy and other was a difficult DP + Bitmask problem.
Coding part had more weightage than Aptitude.

Q1. K Centers
In Ninja Land there are ‘N’ cities numbered from 0 to ‘N’-1. The distance between each pair of cities is given by N * N matrix ‘DIST’ where ‘DIST[i][j]’ denotes the distance between city ‘i’ and ...read more
Ans. Brute force
This problem is an NP-Hard problem i.e there exists no polynomial-time solution for it. So we cannot do anything more than brute force for the exact solution. See this link for more information.
 
Algorithm
• This is a recursive algorithm.
• Create an empty integer list/vector ‘SELECTED’ of size ‘N’.
• Initialize an integer variable ‘RESULT’:= INF.
• We make a recursive function, let it be kCenterHelper(K, N, SELECTE...read more
Answered by CodingNinjas
Add your answer
Q2. Beautiful String
Suppose we are given an empty string “inputString”. We have to convert this “inputString” into a “Beautiful String”
We can perform any number of operations on “inputString” to convert it...read more
Ans. Brute Force
The idea is to insert “abc” at every position in a string , “helperString” (initialised as an empty string) recursively and comparing it with the input string “inputString” at every recursive step. If the “helperString” comes out to be equal to input string “inputString” then return “True” to the function else “False”.
 
Algorithm:
 
• First make a recursive boolean  function “Solve” and pass “helpe...read more
Answered by CodingNinjas
View 2 more answers

Round duration - 90 minutes
Round difficulty - Medium

There were 3 interviewers in my panel. The most senior panellist asked q. related to my interests and internship experience.
Other 2 asked questions related to Coding and subjects. There was 1 coding question which was implementation based and involved many corner cases. They were checking if I was able to figure out different corner cases and handle those. 
There were situation based questions also asked. One question was on system design of Arogya Setu App.

Q1. Multiplying Complex Numbers
You are given two complex numbers 'NUM1' and 'NUM2' as strings, “A+Bi” where ‘A’ represents the real part and ‘B’ represents the imaginary part.
You have to fi...read more
Ans. Mathematics
Let first and the second complex number be, ‘a + bi’ and ‘c+di’, then 
 
'RESULT' = (a + bi) *(c + di) = (ac + adi) = (bci + bd * (-1)) as i^2 = -1
 
‘RESULT’ = (ac - bd) + (ad+ bc) i 
 
The steps are as follows:
 
1. We will parse the input and extract the real and imaginary parts of the number.
2. Let ‘REAL1’, ‘IMG1’ store the real and imaginary part of the first number.
3. Let ‘REAL2’, ‘IMG2’ ...read more
Answered by CodingNinjas
Add your answer

Round duration - 30 minutes
Round difficulty - Easy

HR round involved basic questions related to background and behaviour. It was basically a cultural fit round.

Q1. Basic HR Questions
Tell me about yourself.
Why should we hire you?
How do you handle pressure?
Add your answer

Round duration - 70 Minutes
Round difficulty - Medium

There were 5 people in the zoom meet, including me. Rest all 4 were interviewers, 3 from India and 1 from the United Kingdom.
They started with my introduction and then moved on to the questions from my resume, starting with my internship at Samsung Bangalore and then projects.
Then another interviewer asked about my weakness and strength. Then comes the turn of coding questions.
Starting with finding the minimum element in O(1) time, rotating the 2-D array by 90 degrees, OOPS questions were also asked like- polymorphism, abstraction, virtual class. Some OS questions were- cache, paging algorithms.
Then come my POR and other activities.

Q1. Kth Smallest Element
You are given an array of integers 'ARR' of size 'N' and another integer 'K'. Your task is to find and return 'K'th smallest value present in the array.
...read more
Ans. Brute Force
1. Sort the elements of ‘ARR’ using function ‘SORT’
2. Return element at ('K' - 1)th index
Space Complexity: O(1)Explanation:
O(1).
 
Since we are not using any extra space.
Time Complexity: O(nlogn)Explanation:
O(N * logN) where ‘N’ is the number of elements in the array.
 
As we are sorting the array which takes O(N * log(N)) time.
Answered by CodingNinjas
View 2 more answers
Q2. Inplace rotate matrix 90 degree
You are given a square matrix of non-negative integers of size 'N x N'. Your task is to rotate that array by 90 degrees in an anti-clockwise direction without using ...read more
Ans. Cycle rotation
1. There are N/2  cycles in a matrix of size ‘N’.
2. We traverse in the matrix from the outermost cycle, i.e. (0,0) to innermost cycle i.e. ((N/2)-1, (N/2)-1).
3. For each cycle, we’ll swap the elements of the matrix in a group of four elements i.e. for each ‘i’ <= ‘j’ < ‘N-i-1’ for each 0 <= ‘i’ <= ‘(N/2)-1’ we swap:
   • ‘ARR[i] [j]’ with ‘ARR[j, N-1-i]’
   • ‘ARR[j, N-1-i]’ with ‘ARR[N-1-i, N-1-j]’
   • ‘ARR[N-1-i...read more
Answered by CodingNinjas
View 1 more answer
Q3. OS Questions
What are page replacement algorithm in Operating System?
Add your answer