FabHotels Lead Software Engineer Interview Questions and Answers

Coding Questions and SQL

Q1. Topics : Trees and LinkedList
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Q1. Trees, LinkedList and SQL queries
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Q1. Basic Php ,Oops
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Q1. Security questions
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3 data structure problem with medium to hard level leetcode type.

Q1. 1st question was on vertical order traversal in a tree. it was from gfg he also told me to optimise it
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Q2. 2nd question was from leetcode ie meeting rooms ll , medium question
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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 Complete Journey in Triangular Pyramid
Given a triangular pyramid with vertices marked as ‘O’, ‘X’, ‘Y’, and ‘Z’, and an integer 'N', you need to calculate the number of ways Bob can start a...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
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Q2. 
Maximum Profit Problem Statement
Mukesh is evaluating the maximum profit from his business over a series of days. Given a list of profits over 'N' days, Mukesh wants to determine the highest profit achiev...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
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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 Problem
Given a stream of integers, calculate and print the median after each new integer is added to the stream.
Output only the integer part of the median.
Example:
Input:
N = 5  
Stre...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
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Q2. 
Boundary Traversal of a Binary Tree
Given a binary tree of integers, your task is to return the boundary nodes of the tree in Anti-Clockwise direction starting from the root node.
Input:
The first line ...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
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Q3. 
Count Pairs with Given Sum
Given an integer array/list arr and an integer 'Sum', determine the total number of unique pairs in the array whose elements sum up to the given 'Sum'.
Input:
The first line c...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.
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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 Problem Statement
Given a string 'STR' of length 'N' and an integer 'M' representing the number of rows in the zig-zag pattern, your task is to return the string formed by concatenating all...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
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Q2. 
Ways To Make Coin Change
Given an infinite supply of coins of varying denominations, determine the total number of ways to make change for a specified value using these coins. If it's not possible to make...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
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Round duration - 90 Minutes
Round difficulty - Hard

Timing was 11 am. Platform was quite well.

Q1. 
Rat in a Maze Problem Statement
You need to determine all possible paths for a rat starting at position (0, 0) in a square maze to reach its destination at (N-1, N-1). The maze is represented as an N*N ma...read more
Ans. Bactracking
Approach: We can start the traversal of the paths from the rat’s starting position, i.e. (0,0) keeping track of the visited cells during the traversal. We will recursively go through all the paths possible until the last index of the grid (destination) is reached, and add the path information using which the rat successfully reached the end.
 
Algorithm is as follows:
 
1. Take the starting position of th...read more
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Q2. 
Minimum Cost to Destination
You are given an NxM matrix consisting of '0's and '1's. A '1' signifies that the cell is accessible, whereas a '0' indicates that the cell is blocked. Your task is to compute ...read more
Ans. Backtracking
Maintain a visited array and try to explore all the possibilities with the help of backtracking.
1. Start with (0, 0) and mark it as visited and try to move in all 4 directions.
2. Say at any point we are at (i, j) then the cost of reaching (x,y) will be the minimum of these four cases.
   1. Option 1 -  Left: cost of reaching from (i, j-1)
   2. Option 2 - Right: cost of reaching from (i, j+1)
   3. Option 3 - Up: 1 + cost of rea...read more
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Round duration - 90 Minutes
Round difficulty - Easy

Q1. 
Position of Right Most Set Bit
Determine the position of the rightmost set bit in the binary representation of a given number N.
Input:
T: Number of test cases
N: An integer for which the position of the...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Water Jug Problem Statement
You have two water jugs with capacities X and Y liters respectively, both initially empty. You also have an infinite water supply. The goal is to determine if it is possible to...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Coding Rond consisted of 3 questions

Q1. 1. Data structures and algorithms
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Q2. 2. Computer fundamentals
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Q3. Revise all cs fundamentals
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