SDE - 1 Expedia Group interview experience | Yash Singh

Interview rounds

Round

Easy

Online Coding Interview

Duration75 minutes

Interview date28 Nov 2020

Coding problem3

This round was conducted in Hackerrank portal for a total duration of 75 minutes and was divided into 4 sections.

1st Section : Aptitude Section : 14 questions , 28 minutes
2nd Section : Technical Section : 12 questions , 17 minutes
3rd Section :1 coding Questions : 20 minutes+30 minutes

This Round was Conducted on Hackerrank (Webcam Enabled).

1. DBMS

Write a query that prints a list of employee names (i.e.: the name attribute) for employees in Employee having a salary greater than $2000 per month who have been employees for less than months. Sort your result by ascending employee_id.

Problem approach

Tip 1: Even though DS and Algo is the base for any tech interview, don't take lightly your core branch courses.

Tip 2: Do practice for SQL Queries.

2. Find Bugs in Code

Given a Problem Statement and a Code we need to find the bug in the code and correct the given code.

Problem approach

Tip 1: Other than writing code we must be able to understand others code as well.

3. Count nodes within K-distance

Hard

10m average time

90% success

0/120

Asked in companies

You are given a connected, undirected and acyclic graph with some of the nodes as marked and a positive number 'K'. You need to return the count of all such nodes which have a distance from all marked nodes less than 'K', which means every node whose distance from all marked nodes is less than 'K', should be counted in the result.

A graph is said to be connected if there is a path between every pair of vertex, i.e., from every vertex to any other vertex, there should be some path to traverse and acyclic means that the graph does not contain cycle and undirected means that the edge is bidirectional and one can move in both directions.

Example:

Marked Nodes are Circled with red colour.

Now consider this example of the graph. Here nodes 1,2, and 4 are marked, and let us take the value of K as 3, i.e., we have to find all the nodes at a distance less than 3 from all the marked nodes. We can see that nodes with index 5,9,8,2,0,7 have distances less than 3 from all marked nodes; therefore, the total count of nodes will be 6.

Problem approach

I knew that this has to be done in O(n logn ) or less time complexity so I approached in this way :

Intuition

From root, say the target node is at depth 3 in the left branch. It means that any nodes that are distance K - 3 in the right branch should be added to the answer.

Algorithm

Traverse every node with a depth first search dfs. We'll add all nodes x to the answer such that node is the node on the path from x to target that is closest to the root.

Try solving now

Round

Medium

Video Call

Duration90 minutes

Interview date8 Dec 2020

Coding problem5

I was shared a link of Google Meet and the Google Docs was shared where there was 1 coding problem to be coded there and then the code was run on an IDE to check the sample tests.
Then the interview was followed by a lot of Operating System and Computer System Architecture Questions.
There were 2 Interviewers and both were helpful.
The timing was from 2:30 PM to 4:00 PM

1. Largest subarray with equal number of 0s and 1s

Moderate

10m average time

85% success

0/80

Asked in companies

You are given an array consisting of 0s and 1s. You need to find the length of the largest subarray with an equal number of 0s and 1s.

For example:

If the given array is: [0, 0, 1, 0, 1] The largest subarray would be: [0, 1, 0, 1] (last 4 elements) having length 4.

Problem approach

Approach : I changed array entry for 0 to -1.
Then I took Prefix sum of array and then the problem changed to finding two index in array such that arr[i]=arr[j] and abs(j-i) is maximum.
Time Complexity : O(n) where n= number of elements in array.
Space Complexity : O(n)

Try solving now

2. Computer System Architecture

What is TLB? Why is it used? What are huge pages and their advantages? Which is accessed first TLB or cache? Can we access TLB and cache in parallel?

Problem approach

My Answer :
Huge pages are larger in size and require less number of TLB entries for the same amount of memory. This leads to larger virtual address space being cached and hence better performance. Out of TLB and cache, TLB is accessed first because virtual memory address must first be translated to the physical memory address and then this address is used to access data from the cache. TLB and cache can be accessed in parallel if the cache is flushed everytime TLB is flushed.

Tips : Revise your Core Subjects before appearing in Interviews.

3. System Architecture

How are system calls made at assembly level? How are IO operations like cout translated at low level?

Problem approach

System calls are made through software interrupts (int 0x40 in x86 architecture) and system call number and system call parameters are given as parameters to the software interrupt handler. IO operations like cout internally make system calls (write system call in this case to stdout) to a file descriptor.

Tips : Know the basic working of your commands .
Revise your Core Subjects before appearing in Interviews.

4. Computer System Architecture

Discussion about how the file system is stored on disk and how it works.

Problem approach

Ans:- Explained him about xv6 file system. Explained mainly directory inodes, file inodes and data blocks. Explained how ls accesses this hierarchical structure to retrieve all the files and directories in the directory

5. Computer System Architecture

Distinguish between RISC and CISC architectures.

Problem approach

Ans:-Take a look at this https://superuser.com/questions/883330/what-is-the-difference-between-intel-cisc-and-arm-risc-architecture.

Round

Easy

HR Round

Duration45 minutes

Interview date10 Dec 2020

Coding problem4

The round was held on Google Meet with HR from 2:30 PM to 3:15 PM.
The HR was friendly and asked the basic questions.

1. You have changed jobs/jumped ship already, why so?

Problem approach

My ans -

My switches have helped me develop better interpersonal skills, gain diverse skills and adapt to rapidly changing business environments.

I can solve problems more efficiently and creatively, as I have learned to live with ambiguity and uncertainty. My first job helped me develop patience.

My second job helped me master spreadsheets and numbers.

My third job helped me develop better people skills and also adjust amidst culturally diverse and geographically dispersed teams.

All in all, I feel that my varied background makes me an ideal candidate for this job role today.

2. If I call up your current or previous reporting manager now, what will be their opinion about you? What will they say that you need to work on?

Problem approach

Tips : Have good relations wherever you work .

My answer-

I used to get nervous while speaking in front of large groups. You can say that I had stage-fear, and I believe that I still do.
This is partly because I am shy by nature. No wonder that I have been always assigned Individual Contributor roles.
My current manager might cite this as one of my weaknesses, and he has actually helped me to overcome my shyness.
I am working to improve my public speaking, and leadership skills and I am sure my future employer will witness a blatant change in me

3. Where do you see yourself 3 years from now? Where do you see yourself in 5 years?

Problem approach

My current goal is to find a career spot that ensures continued growth alongside new challenges daily.

3 years from now, I see myself as an experienced and reliable senior in the team and 5 years from now, I assume that I will be ready to take up managerial responsibilities like product strategy.

I want to have a stable career in a single organization and hope I will get the same wherever I start.

4. Did you ever have a conflict with your current/previous boss or professor?

Problem approach

My answer -

Recently I had a disagreement with one of my professors about a question that was out of syllabus in one of the semester exams.

It was not a major one, but yes I will label it a ‘conflict’.

Most of my friends and peers did not attempt this question due to ambiguity.

When I brought the cause into my professor’s notice in private, he remained cold and unconcerned.

So, I and my batchmates had a discussion following which, we went to him together.

At that point, our professor agreed that the question was ambiguous, but he refused to give us grace marks for the same.

I felt disappointed because he did not appreciate the fact that I brought the situation earlier, into his notice in private.

Besides, he did not suggest an alternative paper or project work, with which students could make up for the lost marks.