SDE - 1 Quikr interview experience | Anonymous

Interview rounds

Round

Easy

Online Coding Test

Duration60 minutes

Interview date27 Jul 2015

Coding problem2

This was a coding test where we had to solve 2 coding questions in 60 minutes.

1. Buy and Sell Stock

Hard

0/120

Asked in companies

You are Harshad Mehta’s friend. He told you the price of a particular stock for the next ‘n’ days.

You are given an array ‘prices’ which such that ‘prices[i]’ denotes the price of the stock on the ith day.

You don't want to do more than 2 transactions. Find the maximum profit that you can earn from these transactions.

Note

1. Buying a stock and then selling it is called one transaction.

2. You are not allowed to do multiple transactions at the same time. This means you have to sell the stock before buying it again.

Example:

Input: ‘n’ = 7, ‘prices’ = [3, 3, 5, 0, 3, 1, 4].

Output: 6

Explanation: 
The maximum profit can be earned by:
Transaction 1: Buying the stock on day 4 (price 0) and then selling it on day 5 (price 3). 
Transaction 2: Buying the stock on day 6 (price 1) and then selling it on day 6 (price 4).
Total profit earned will be (3 - 0) + ( 4 - 1) = 6.

Problem approach

The goal is to discover a local minimum of every growing sequence by traversing the given list of prices. We can make the most money by purchasing shares at the beginning of each ascending sequence (local minimum) and selling them at the end (local maximum).
Steps :
1.Find the local minima and store it as starting index. If not exists, return.
2.Find the local maxima. and store it as an ending index. If we reach the end, set the end as the ending index.
3. Update the solution (Increment count of buy-sell pairs)
4. Repeat the above steps till the end is not reached.

Try solving now

2. Subsequences of String

Moderate

15m average time

85% success

0/80

Asked in companies

You are given a string 'STR' containing lowercase English letters from a to z inclusive. Your task is to find all non-empty possible subsequences of 'STR'.

A Subsequence of a string is the one which is generated by deleting 0 or more letters from the string and keeping the rest of the letters in the same order.

Problem approach

Recursion can be used to solve this problem. For every character of the input string there are two options, one is to include it in the current subsequence and another is not including it in the current subsequence. This will lead to all possible subsequences of the input string.
Algorithm:
Take an empty set and an empty list to store all the subsequences.
Base Case: If there are no more characters in the string to include in the current subsequence, that means that the current subsequence is done.
Check if the current subsequence already exists in our answer, otherwise append it in the final answer.
If there are still letters left to process in the input string:
Iterate over the letters and once append the current letter in the current subsequence and proceed further.
And once don’t include the current letter in the current subsequence and proceed further.

Try solving now

Round

Easy

Face to Face

Duration60 minutes

Interview date29 Jul 2015

Coding problem2

This was a technical round where the interviewer asked me questions related to OS and Java.

1. OS Question

What is critical section problem?

Problem approach

Critical section is the code segment of a process in which the process may be changing common variables, updating tables, writing a file and so on. Only one process is allowed to go into critical section at any given time (mutually exclusive).The critical section problem is to design a protocol that the processes can use to
co-operate. The three basic requirements of critical section are:
1. Mutual exclusion
2. Progress
3. bounded waiting
Bakery algorithm is one of the solutions to CS problem.

2. Java Question

How can we create a thread in java?

Problem approach

There are two ways to create a thread in Java:
1) By extending Thread class :
The Thread class provides constructors and methods for creating and operating on threads. The thread extends the Object and implements the Runnable interface.
// start a newly created thread.
// Thread moves from new state to runnable state when it gets a chance, executes the target run() method
public void start()
2) By implementing Runnable interface.
Any class with instances that are intended to be executed by a thread should implement the Runnable interface. The Runnable interface has only one method, which is called run().
// Thread action is performed
public void run()

Round

Easy

HR Round

Duration30 minutes

Interview date29 Jul 2015

Coding problem2

Typical HR round with behavioral questions.

1. Basic HR Questions

1. Asked many questions about work in current workplace
2. How my current job work can be used in Quickr?
3. Some more questions asked related to work done in current job and how can it be useful in Quikr?

Problem approach

Tip 1 : The cross questioning can go intense some time, think before you speak.
Tip 2 : Be open minded and answer whatever you are thinking, in these rounds I feel it is important to have opinion.
Tip 3 : Context of questions can be switched, pay attention to the details. It is okay to ask questions in these round, like what are the projects currently the company is investing, which team you are mentoring. How all is the work environment etc.
Tip 4 : Since everybody in the interview panel is from tech background, here too you can expect some technical questions. No coding in most of the cases but some discussions over the design can surely happen.