Oyo Rooms Software Developer Interview Questions, Process, and Tips

3 coding questions and platform was hackerrank

Q1. Some medium Graph problems from leetcode
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Q1. Dictionary Sort , DFS, BFS
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Q1. Reverse a LinkedList from m to n
Ans. 
Reverse a LinkedList from m to n
• Traverse the list to m-1th node

• Reverse the nodes from m to n

• Connect the reversed list to the original list
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Round duration - 90 Minutes
Round difficulty - Easy

This round was conducted on the HackerEarth platform. It had 2 sections and candidates were given a time of 1 hour 30 minutes. 

Programming MCQs — 18 MCQs (each of 2 marks)
Questions were a little tricky. it tested upon one’s programming fundamentals. It had C/C++ output questions, pseudocode questions, Operating systems, and SQL queries.
Coding — 2 ( one contains 75 marks and the other contains 100 marks )

Our scores of the first 2 sections weren’t revealed. My MCQs went really well. I solved 2 coding questions in the coding section. Only 15 students got selected for the interview round, and I was one of them.

Q1. Count Ways To Travel Triangular Pyramid
Bob has been given a triangular pyramid with its vertices marked as ‘O’, ‘X’, ‘Y’ and ‘Z’ and provided with another integer ‘N’. In a single step, Bob can go to any ...read more
Ans. Brute Force
The idea is very simple, as standing at any point we will always have three choices to move. So we will make a recursive function and call it for all three choices and decrease ‘N’ by 1 each time. So when ‘N’ will reach 0 then we will check the current position, if it is ‘O’ then we can say we have found a way.
 
Complete Algorithm :
• We will make a helper recursive function named ‘SOLVE’ which will receive...read more
Answered by CodingNinjas
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Q2. Maximum Profit
Mukesh is a hard worker and has a good running business. He has a list of profits he made in the last ‘N’ days. Mukesh wants to know what maximum profit he made in the few consecutive days. ...read more
Ans. Brute Force
The basic idea is to iterate through the given array/list ‘profit’ and check for each index as a starting point, if any possible consecutive days in the range [ ‘A’, ‘B’ ] is possible, calculate its ‘sum’ and update the ‘maxProfit’ if the ‘sum’ is greater than ‘maxProfit’ ( where ‘maxProfit’ denotes the Maximum possible profit from the array/list ‘profit’ under the given range).
 
Algorithm:
 
1. Declare ...read more
Answered by CodingNinjas
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Round duration - 60 Minutes
Round difficulty - Medium

This round was scheduled for 1 hour and the panel had 1 interviewer. Being a virtual interview, the first challenge that I faced was that the interviewer was not audible. I suggest you not panic in such a situation and use the chatbox feature (or contact HR if need be) to figure out something that works for you and the panel. We later connected over voice call (over the phone) with our videos ON (over a laptop) and continued with the interview.

The interview was very calm and helpful. I was able to solve all questions and I explained different approaches to solve the questions. Once he was convinced of my solution, he asked me to write the code on my own IDE.

Q1. Running Median
You are given a stream of 'N' integers. For every 'i-th' integer added to the running list of integers, print the resulting median.
Print only the integer part of the media...read more
Ans. Sorting Approach
The median of n numbers is the middle-most element among the numbers when sorted in ascending order, when n is odd, and is the average of the two middle-most elements, when n is even. To find the middle-most elements, we do this: For every new addition to the stream, we sort all the numbers that are currently present. This makes it easy for us to obtain the middle-most elements.
Space Complexity: O(1)Exp...read more
Answered by CodingNinjas
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Q2. Boundary Traversal
You have been given a binary tree of integers. Your task is to print the boundary nodes of this binary tree in Anti-Clockwise direction starting from the root node.
NOTE:
The boundary ...read more
Ans. Recursion Based Approach
The boundary traversal of a binary tree can be broken down into 4 parts. These parts are given in the same order as they are present in the traversal-
 
1. The root node - The root node will always be our first node in the whole boundary traversal.
    
2. The left boundary - The left most nodes of the left subtree are also included in the boundary traversal, so we will process them next except for...read more
Answered by CodingNinjas
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Q3. Number Of Pairs With Given Sum
You have been given an integer array/list(arr) and a number 'Sum'. Find and return the total number of pairs in the array/list which when added, results equal to the ...read more
Ans. Brute Force Approach
• Initialize the ans = 0
• Run two loops first from i = 0 to n-1 and second from j = i+1 to  n-1 and if arr[i] + arr[j] == Sum then increase the ans by 1.
• Return ans
Space Complexity: O(1)Explanation:
O(1)
 
As constant extra space is used.
Time Complexity: O(n^2)Explanation:
O(N^2), where N is the size of the array.

As we are running two nested loops of size N.
Answered by CodingNinjas
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Round duration - 90 Minutes
Round difficulty - Medium

This was a technical + HR round. First, he asked me to introduce myself. This round was also based on your knowledge of DSA. I was asked 2 coding questions. Then he asked a couple of questions from OS and DBMS which were pretty easy. At last, we ended the interview on a good note. Then he asked me questions about myself.
Why I want to join OYO rooms. 
What are my hobbies?
Goals in the next five years.

Q1. Zig-Zag String
You are given a string ‘STR’ of size ‘N’ and an integer ‘M’ (the number of rows in the zig-zag pattern of ‘STR’). Your task is to return the string formed by concatenating all ‘M’ rows when ...read more
Ans. Iteration
Create an array ‘arr’ of size ‘m’, use the array index ‘arr[i]’ to store the string at row ‘i’. Traverse the string ‘str’, identify the character’s row in the current iteration, and append that character to its corresponding row/index in ‘arr’.
 
1. Create an array of strings named ‘arr’ of size ‘m’.
2. Initialize variable ‘curRow’ with value 0 and ‘move’ with value 1. Use ‘curRow’ to identify the character’s row ...read more
Answered by CodingNinjas
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Q2. Ways To Make Coin Change
You are given an infinite supply of coins of each of denominations D = {D0, D1, D2, D3, ...... Dn-1}. You need to figure out the total number of ways W, in which you can make a cha...read more
Ans. Recursion
 
1. The idea is to use recursion.
2. For a particular coin, we have two options either include it or exclude it.
3. If we include that coin, then calculate the remaining number that we have to generate so recur for that remaining number.
4. If we exclude that coin, then recur for the same amount that we have to make.
5. Our final answer would be the total number of ways either by including or excluding.
6. There will be two edg...read more
Answered by CodingNinjas
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Q1. Operating system questions
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Linked list standard questions

Round duration - 90 Minutes
Round difficulty - Easy

Q1. Position of Right Most Set Bit
You are given a number N. You need to return the position of the rightmost set bit.
For example:
If the given number is 10 with the binary representation: 1010
The rightmo...read more
Ans. Brute Force
• Check each bit starting from right to left.
• Return the first bit you encounter which is 1.
• The given number is <= 10^9. The maximum number of bits can be 32.
• We can make a loop of 32 and check each bit if it is on or off.
• This can be done by left shifting 1 with i (in the loop) and taking AND of this with the given number.
Space Complexity: O(1)Explanation:
O(1)
In the worst case, no extra constant space is req...read more
Answered by CodingNinjas
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. Water Jug Problem
You are given two water jugs with capacities X and Y litres respectively. Both the jugs are initially empty. There is an infinite amount of water supply available. The jugs do not have ma...read more
Ans. Using BFS
We will run a breadth-first search(BFS), keeping states as water present in both the jugs. We will visit all the states, keeping a hashmap for visited states to not revisit the same state. If we reach a state such that the capacity of water in one of the jugs is equal to ‘Z’ liters or the sum of water in both the jugs is equal to ‘Z’ liters we return true else we return false. 
 
Below is the detailed ...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. Technical Questions
Questions on DBMS, Os, Puzzles, Your projects.
What is indexing?
CPU Scheduling algos.
Ans. 
Tip 1 : explain your solution step by step so that they don't need to ask twice.
Tip 2 : don't give up so easily even if you don't know the things. sometimes interviewers also help if you try to find the solution. 
Tip 3 : be confident
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