SDE - 2 Rakuten India interview experience | Vishnu ChaturVedi

Interview rounds

Round

Medium

Video Call

Duration60 minutes

Interview date17 Aug 2021

Coding problem1

My first round of interviews was scheduled for at 17-Aug-2021 10 AM IST. I joined 5 minutes early so that I could test my microphone etc. and other technical issues. Once interviewer joined the interview, a Hackerrank link was shared to me which contained the problem statement. The interviewer was very friendly and helped me to understand the problem statement whenever any help was required. I successfully completed the online coding round and was able to pass all the edge test cases.

1. Longest Substring Without Repeating Characters

Moderate

30m average time

65% success

0/80

Asked in companies

Given a string input of length n, find the length of the longest substring without repeating characters i.e return a substring that does not have any repeating characters.

Substring is the continuous sub-part of the string formed by removing zero or more characters from both ends.

Problem approach

Step 1: Unique ArrayList to keep track of substrings (for easy debugging).
Step 2: Set to store letters and check for duplication
Step 3: Initialized two int variables i, j to 0.
Step 4: Initialized a distance variable to keep track of distance between i and j
Step 5: Iterate through the while loop for i and j < string length and if there are no duplicates, widen the window: extend "j" while fixing "i".
Step 6: if there are duplicates, keep removing from the left side "using the i index" till you get rid of that initial letter causing duplication in other words, shorten the window by moving i to right while fixing j

Try solving now

Round

Hard

Video Call

Duration60 minutes

Interview date18 Aug 2021

Coding problem3

The interview was scheduled on 18-Aug-2021 at 10 AM IST. As usual, I joined 5 minutes early and verified if there are no technical glitches from my end. The interviewer joined on the time and asked about myself.

Then he gave his introduction and about his responsibilities in the company. The interview started and he started asking questions on JAVA/JAVA8, Springboot, and Kubernetes. I was also asked to code for the below implementations.

* Builder Pattern
* Singleton class
* Iterate and employee list and then sort it in ascending order using JAVA8 streams.

#System Design
I was asked to design an Online airline reservation system and after explaining the approach, I was asked the below questions

* What if two users are booking the same seat and that seat is booked by one of them, How we will be disabling the option to other user to book the same seat
* Payment gateway integration
* Concurrency implementation

1. Java Technical Questions

In Java, the Interviewer asked me the below questions

* Difference between Hashmap and Hashtable.
* Internal Working of Hashtable.
* Implement builder pattern.
* Design a singleton class.
* Design a thread-safe class.
* Features of JAVA 8
* Iterate an employee list and then sort it in ascending order of salary using JAVA 8 streams.

Problem approach

Tip 1: You should be good with language basics.
Tip 2: Always improve. always advance

2. Springboot questions

Interviewer asked me the below questions from the Springboot.
* List all the stereotype annotations.
* Scenario based question based on the annotations such as implementing atomicity for the transactions, Error handling etc.
* Developing a simple REST API and connect with H2 database.

Problem approach

Tip 1: You should have good knowledge of the Springboot framework.
Tip 2: API knowledge comes from coding practice. Have fun by developing APIs. Follow Baeldung for spring boot preparation.

3. System Design Question

Design a simple online airline reservation system. After the explanation, the Below questions were asked.
* What if two users are booking the same seat and that seat is booked by one of them, How we will be disabling the option to other user to book the same seat
* Payment gateway integration
* Concurrency implementation

Problem approach

Tip 1: Understand System design and read case studies such as Uber etc.
Tip 2: Always take care of Concurrency, Load balancing and caching mechanisms.
Tip 3: Understand SOLID principles.

Round

Medium

Video Call

Duration1 hour

Interview date19 Aug 2021

Coding problem2

This interview round was a technical discussion with the Remote manager working from the Singapore location.
* He joined on the time and was very polite and helped during the whole interview.
* He asked me the below questions based on data structure and algorithms.
# Convert Binary Tree to an Array using JAVA.
# Find if the given singly linked list has a cycle and explain the approach. It was a code pair round.

1. Flatten BST To A Sorted List

Moderate

30m average time

70% success

0/80

Asked in companies

You have been given a Binary Search Tree (BST). Your task is to flatten the given BST to a sorted list. More formally, you have to make a right-skewed BST from the given BST, i.e., the left child of all the nodes must be NULL, and the value at the right child must be greater than the current node.

A binary search tree (BST), also called an ordered or sorted binary tree, is a rooted binary tree whose internal nodes each store a value greater than all the values in the node's left subtree and less than those in its right subtree.

Follow Up :

Can you solve this in O(N) time and O(H)  space complexity?

Problem approach

Step 1: I started with creating a method with the input as BST node
Step 2: Then I initialized an ArrayList and performed recursions for the below conditions
# if the node's left value is not null then keep adding the elements to the ArrayList.
# if the node's right value is not null then keep adding the elements to the arraylist.
Step 3: Finally, convert the result ArrayList to an array using toArray().

Try solving now

2. Cycle Detection in a Singly Linked List

Moderate

15m average time

80% success

0/80

Asked in companies

You are given a Singly Linked List of integers. Return true if it has a cycle, else return false.

A cycle occurs when a node's next points back to a previous node in the list.

Example:

In the given linked list, there is a cycle, hence we return true.

Problem approach

Step 1: Initilaize "fast" and "slow" nodes and assign head to them.
Step 2: If head is null return 0.
Step 3: Iterate using while loop to check if fast != null and fast.next != null
# If true, then slow = slow.next and fast =fast,next.next
# if slow == fast, return 1;
0 = No cycles
1 = Cycles presents.

Try solving now

Round

Medium

Video Call

Duration1 hour

Interview date20 Aug 2021

Coding problem1

This interview round was with the Department managers working from the Tokyo location. They joined on the time and asked about me and also they did give their introduction. They were very polite and helping,

They asked the below scenario based questions about Kubernetes such as:

* How to find the root cause if any one of the pods is throwing "Out of Memory" alerts,
* Basic knowledge of Kubernetes.

1. Operating System Questions

* How to find the root cause if any one of the pods is throwing "Out of Memory" alerts, (I answered "It can be because Node is running out of resources, Hence we need to increase the CPU and RAM size)
* Basic knowledge of Kubernetes.

Problem approach

Tip 1: Good knowledge of Container orchestration is required.
Tip 2: Learn Kubernetes and practice a lot.

Round

Easy

Telephonic

Duration30 minutes

Interview date20 Aug 2021

Coding problem2

This was a telephonic round with the India manager. HR already informed me that I can expect a call from the India manager. So I got a call from his side at 4 PM IST. He was very polite and it was nice talking with him.
* He asked about me and my technical skills.
* He informed me about the project and the responsibilities I need to serve.
* He did ask me 2 puzzles to check my analytical skills.
# Given 8 balls and 1 balance to compare the weights. Out of 8 balls, 1 ball weighs more than the other 7 balls. How to find that?
# There are two rooms separated by a single door. In one room there are 3 switches, and in another room, there are 3 bulbs, I need to find which switch belongs to which bulb. Condition: We can go only a single time from one room to another room.

1. Puzzle

Given 8 balls and 1 balance to compare the weights. Out of 8 balls, 1 ball weighs more than the other 7 balls. How to find that?

Problem approach

Tip 1: Take your time and understand the problem and then you can easily solve the analytical problems.
Tip 2: Practice from India bix.

2. Puzzle

There are two rooms separated by a single door. In one room there are 3 switches, and in another room, there are 3 bulbs, I need to find which switch belongs to which bulb. Condition: We can go only a single time from one room to another room.

Problem approach

Tip 1 : Take your time and understand the problem and then you can easily solve the analytical problems.
Tip 2 : Practice from India bix.

Round

Easy

HR Round

Duration60 minutes

Interview date20 Aug 2021

Coding problem1

HR round was the final round. It was scheduled at 6 PM IST. So HR joined on time and greeted me and asked me about How I am doing and about my hobbies and interests.

1. Basic HR questions

* He asked me about my experience with the interview.
* He discussed the compensation part and joining formalities such as Offer letter generation etc..