Ola interview experience Real time questions & tips from candidates to crack your interview

SDE - 2

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4 rounds | 5 Coding problems

Interview preparation journey

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Preparation
Duration: 2 months
Topics: Linked List, Stacks, Queues, Tree, Graph, System Design, Dynamic Programming.
Tip
Tip

Tip 1 : Prepare Data Structures topic by topic and also solve at least 10 interview questions from each topic. The have a list of excellent questions. 
Tip 2 : For system design try to take few questions by yourself and think of what different scenarios can arise considering it as a distributed system. There are multiple topics like Consistent Hashing, Partition tolerance, Availability, Sharing etc which needs special attention. The interviewers will dig them deep and will try to see how much of it you actually understand. 
Tip 3 : Also please do focus on LLD. Sometimes they can ask you to write sample code for problems. Try solving 4-5 problems. 
Tip 4 : You should do and prepare properly 2 -3 projects and try deploying it. You will face a lot of new challenges which you do not face in normal day to day usage.

Application process
Where: Referral
Eligibility: NA
Resume Tip
Resume tip

Tip 1 : You can go for 1 page resume, though it is not necessary. Mention about your projects, your actual contribution, languages that you have used in that project etc. 
Tip 2 : You should always put your academic achievements. Sometimes it gains interviewers attention. 
Tip 3 : Make it a little bit colourful rather than plain white.

Interview rounds

01
Round
Medium
Online Coding Interview
Duration60 minutes
Interview date14 Jul 2021
Coding problem1

It was a problem solving round where a hackerrank link was given containing 2 questions.
You have to solve them within 90 minutes.
I was asked to solve it within a week.

1. Find all distinct palindromic substrings of a given string

Moderate
20m average time
80% success
0/80
Asked in companies
MakeMyTripOlaSAP Labs

Ninja did not do homework. As a penalty, the teacher has given a string ‘S’ to ninja and asked him to print all distinct palindromic substrings of the given string. A string is said to be palindrome if the reverse of the string is the same as the string itself. For example, the string “bccb” is a palindrome, but the string “def” is not a palindrome.

Problem approach

Step 1 : Find all the palindromic sub-strings
Step 2 : Remove duplicate palindromes
Step 3 : Print the distinct palindromes and number of such palindromes

Try solving now
02
Round
Easy
Face to Face
Duration60 minutes
Interview date17 Jul 2021
Coding problem2

2 questions was asked by the interviewer. You have to clearly explain your approach and write a working solution. He even asked me to run on some additional test cases

1. Job Sequencing Problem

Moderate
30m average time
70% success
0/80
Asked in companies
OracleCIS - Cyber InfrastructureExpedia Group

You are given a 'Nx3' 2-D array 'Jobs' describing 'N' jobs where 'Jobs[i][0]' denotes the id of 'i-th' job, 'Jobs[i][1]' denotes the deadline of 'i-th' job, and 'Jobs[i][2]' denotes the profit associated with 'i-th job'.


You will make a particular profit if you complete the job within the deadline associated with it. Each job takes 1 unit of time to be completed, and you can schedule only one job at a particular time.


Return the number of jobs to be done to get maximum profit.


Note :
If a particular job has a deadline 'x', it means that it needs to be completed at any time before 'x'.

Assume that the start time is 0.


For Example :
'N' = 3, Jobs = [[1, 1, 30], [2, 3, 40], [3, 2, 10]].

All the jobs have different deadlines. So we can complete all the jobs.

At time 0-1, Job 1 will complete.
At time 1-2, Job 3 will complete.
At time 2-3, Job 2 will complete.

So our answer is [3 80].
Problem approach

Sort the jobs based on their deadlines.
Iterate from the end and calculate the available slots between every two consecutive deadlines. Include the profit, deadline, and job ID of ith job in the max heap.
While the slots are available and there are jobs left in the max heap, include the job ID with maximum profit and deadline in the result.
Sort the result array based on their deadlines.

Try solving now

2. Partition Equal Subset Sum

Moderate
25m average time
65% success
0/80
Asked in companies
OlaOracleSAP Labs

You are given an array 'ARR' of 'N' positive integers. Your task is to find if we can partition the given array into two subsets such that the sum of elements in both subsets is equal.

For example, let’s say the given array is [2, 3, 3, 3, 4, 5], then the array can be partitioned as [2, 3, 5], and [3, 3, 4] with equal sum 10.

Follow Up:

Can you solve this using not more than O(S) extra space, where S is the sum of all elements of the given array?
Problem approach

Let isSubsetSum(arr, n, sum/2) be the function that returns true if 
there is a subset of arr[0..n-1] with sum equal to sum/2

The isSubsetSum problem can be divided into two subproblems
a) isSubsetSum() without considering last element 
(reducing n to n-1)
b) isSubsetSum considering the last element 
(reducing sum/2 by arr[n-1] and n to n-1)
If any of the above subproblems return true, then return true. 
isSubsetSum (arr, n, sum/2) = isSubsetSum (arr, n-1, sum/2) ||
isSubsetSum (arr, n-1, sum/2 - arr[n-1])

Try solving now
03
Round
Easy
Face to Face
Duration60 minutes
Interview date21 Jul 2021
Coding problem1

I was asked 1 system design question. The question was to design an online multiplayer game which can be scaled for more than 10 million users. 
The interviewer helped me to collect requirement and also helped me in choosing different low latency protocol to communicate between client and server.

1. System Design Question

Design an online multiplayer game which can be scaled to more than 10 million users. It should be very responsive as well.

Problem approach

Tip 1 : Collect all requirements clearly
Tip 2 : Discuss which type of database you are going to choose and why
Tip 3 : Also discuss how you are going different microservices and why you decided to do it in that way.

04
Round
Medium
Face to Face
Duration60 minutes
Interview date27 Jul 2021
Coding problem1

The interviewer asked few sql based questions and asked me to write the solution.
He also gave 1 problem solving question.

1. DBMS

Question related to join and calculating average of all values from a given table.

Here's your problem of the day

Solving this problem will increase your chance to get selected in this company

Skill covered: Programming

What is recursion?

Choose another skill to practice
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