Musafir.com Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Easy

Technical round with 3 problems based on DSA and Algorithms.

Q1. 
Smallest Integer Not Representable as Subset Sum
Given a non-decreasing sorted array ARR of N positive numbers, determine the smallest positive integer that cannot be expressed as the sum of elements from...read more
Ans. 
Find the smallest positive integer that cannot be expressed as the sum of elements from any proper subset of a given array.
• Sort the array in non-decreasing order.

• Iterate through the array and keep track of the smallest sum that can be formed.

• If the next element in the array is greater than the current sum + 1, then the answer is the current sum + 1.

• Return the answer as the smallest integer not representable as a subset
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Q2. 
Reverse Linked List Problem Statement
Given a singly linked list of integers, return the head of the reversed linked list.
Example:
Initial linked list: 1 -> 2 -> 3 -> 4 -> NULL
Reversed link...read more
Ans. 
Reverse a singly linked list of integers and return the head of the reversed linked list.
• Iterate through the linked list and reverse the pointers to point to the previous node instead of the next node.

• Use three pointers to keep track of the current, previous, and next nodes while reversing the linked list.

• Update the head of the reversed linked list to be the last node encountered during the reversal process.
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Q3. 
Smallest Window Problem Statement
Given two strings S and X containing random characters, the task is to find the smallest substring in S which contains all the characters present in X.
Input:
The first...read more
Ans. 
The task is to find the smallest substring in string S which contains all the characters present in string X.
• Iterate through string S and keep track of characters in X using a hashmap

• Use two pointers to maintain a sliding window and find the smallest window containing all characters in X

• Return the smallest window found
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Round duration - 60 minutes
Round difficulty - Easy

Technical round with questions based on OOPS and Angular.

Q1. What are the different OOP concepts?
Ans. 
OOP concepts include inheritance, encapsulation, polymorphism, and abstraction.
• Inheritance allows a class to inherit properties and behavior from another class.

• Encapsulation restricts access to certain components of an object, protecting its integrity.

• Polymorphism allows objects to be treated as instances of their parent class.

• Abstraction hides the complex implementation details of an object and only shows the necessar
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Round duration - 60 minutes
Round difficulty - Easy

Questions based on System Design, ajax, jquery were asked.

Q1. How would you design a traffic light system?
Ans. 
Designing a traffic light system involves creating a system that controls the flow of traffic at intersections.
• Divide the traffic light system into three main lights: red, yellow, and green.

• Implement timers to control the duration of each light.

• Include sensors to detect the presence of vehicles and pedestrians.

• Consider implementing a pedestrian crossing signal.

• Integrate a central control system to coordinate the timing
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Q2. How does AJAX work?
Ans. 
AJAX allows for asynchronous communication between client and server without needing to reload the entire page.
• AJAX stands for Asynchronous JavaScript and XML.

• It allows for sending and receiving data from a server without reloading the entire page.

• AJAX uses XMLHttpRequest object to make requests to the server.

• It can update parts of a web page without requiring a full page reload.

• Commonly used in web applications to pro
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Q3. What is the difference between AngularJS and jQuery?
Ans. 
AngularJS is a full-fledged MVC framework for building dynamic web applications, while jQuery is a lightweight library for DOM manipulation and event handling.
• AngularJS is a full-fledged MVC framework, providing features like two-way data binding, dependency injection, and routing.

• jQuery is a lightweight library primarily used for DOM manipulation and event handling.

• AngularJS is suitable for building single-page applic...read more
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Round duration - 75 minutes
Round difficulty - Easy

This was the online round held at university. All students who met the eligibility criteria were called for the online test on hackerrank.

Q1. 
Anagram Difference Problem Statement
Given two strings, 'STR1' and 'STR2', of equal lengths, determine the minimum number of manipulations required to make the two strings anagrams of each other.
Input:
...read more
Ans. 
The problem involves finding the minimum number of manipulations required to make two strings anagrams of each other.
• Create frequency maps for both strings

• Find the absolute difference in frequencies of each character

• Sum up the absolute differences to get the total manipulations needed
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Round duration - 90 Minutes
Round difficulty - Medium

This round was technical round and the interview started with formal introduction and general questions.
After that We had a discussion on LRU Cache.
Followed by coding and set of data structure questions.

Q1. 
Gas Tank Problem Statement
You have a car with a gas tank of infinite capacity. There are 'N' gas stations located along a circular route, numbered from 0 to N-1. You begin your journey with an empty tank...read more
Ans. 
Find the starting gas station index to complete a circular route with gas and cost arrays.
• Iterate through gas stations, keeping track of total gas and total cost from each station

• If total gas is greater than or equal to total cost, update the starting station index

• Return the starting station index if a valid one is found, else return -1
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Round duration - 90 minutes
Round difficulty - Medium

This Round was DS and Algo round and it started with formal introduction, followed by 2 problems. We first dicussed the approach the time complexity and proper code covering all cases.

Q1. 
Boundary Traversal of Binary Tree
Given a binary tree of integers, your task is to print the boundary nodes of this binary tree in an anti-clockwise direction starting from the root node.
Input:
The fir...read more
Ans. 
Print the boundary nodes of a binary tree in an anti-clockwise direction starting from the root node.
• Traverse the left boundary nodes from the root to the leftmost leaf node.

• Traverse the leaf nodes from left to right.

• Traverse the right boundary nodes from the rightmost leaf node to the root.
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Q2. 
Maximum Sum of Two Non-Overlapping Subarrays
Given an integer array ARR and a positive integer K, your objective is to find two non-overlapping subarrays (contiguous) of length K each, such that their sum...read more
Ans. 
Find two non-overlapping subarrays of length K with maximum sum in an integer array.
• Iterate through the array to find all possible subarrays of length K.

• Calculate the sum of each pair of non-overlapping subarrays of length K.

• Keep track of the maximum sum obtained from the pairs of subarrays.
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Round duration - 30 minutes
Round difficulty - Easy

This was the Final Interview and it started with formal introduction and general HR questions. Then We discussed about the projects and the things written in my resume. The interviewer was very frank and this round was very interactive. He asked me about my college, my future plans, teachers, various subjects, why Expedia and questions like that.

Round duration - 120 minutes
Round difficulty - Easy

The test was divided into two parts : Section A had questions from Quantitative, C language, Logical and English. The second part had two coding questions.

Q1. 
Deletion in Circular Linked List Problem Statement
Given a Circular Singly Linked List of integers, and a specific value 'VAL', your task is to delete the first occurrence of this value in the linked list...read more
Ans. 
Delete the first occurrence of a specific value in a Circular Linked List.
• Traverse the circular linked list to find the value to be deleted.

• Update the pointers to skip the node containing the value.

• Handle edge cases like deleting the only node in the list.

• Return the modified circular linked list.
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Q2. 
LRU Cache Design Question
Design a data structure for a Least Recently Used (LRU) cache that supports the following operations:
1. get(key) - Return the value of the key if it exists in the cache; otherw...read more
Ans. 
Design a Least Recently Used (LRU) cache data structure that supports get and put operations with capacity constraints.
• Use a combination of a doubly linked list and a hashmap to efficiently implement the LRU cache.

• Keep track of the least recently used item and update it accordingly when new items are added.

• Ensure that the cache does not exceed its capacity by evicting the least recently used item when necessary.
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Round duration - 120 minutes
Round difficulty - Easy

Hello everyone! Expedia came to our campus for full time hiring of final year students. They had shortlisted candidates for the interviews by taking an online test comprised of four sections (Quantitative, C, Logical and English). Every section had a timer attached to it, so you need to think and answer quickly. Although, the questions were easy but cutoff was quite high. This round was followed by a coding round, comprised of two questions.

Q1. 
Problem: Deletion in Circular Linked List
You are provided with a Circular Linked List of integers and a specific integer, referred to as 'key'.
Your task is to implement a function that locates the spec...read more
Ans. 
Implement a function to delete a specific key from a Circular Linked List of integers.
• Traverse the Circular Linked List to find the key to be deleted.

• Adjust the pointers to remove the node containing the key.

• Handle the case where the Circular Linked List becomes empty after deletion.

• Return -1 if the Circular Linked List is empty after deletion.
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Q2. 
Page Faults Identification Problem Statement
In computing, a page fault occurs when a process accesses a memory page that is not currently mapped by the memory management unit. To handle new pages being b...read more
Ans. 
The problem involves determining the number of page faults using the Least Recently Used (LRU) replacement algorithm.
• Page faults occur when a process accesses a memory page not currently mapped by the memory management unit.

• Page replacement algorithm like LRU is used to decide which existing page should be replaced.

• The goal is to calculate the number of page faults based on the given input sequences and memory capacity...read more
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Round duration - 60 minutes
Round difficulty - Easy

The man who was taking my first round was my alumni. He started-off by asking my introduction and then gave me 2 programming questions to code. He then navigated on to my Codechef profile and asked a question that I did in the June 14 Long Contest. I explained him and he was satisfied. 
Tips : You don’t have to answer the stuffs quickly, rather you need to develop some test cases and have some discussion regarding the structure of the problem, and then answer.

Q1. 
Cycle Detection in a Singly Linked List
Determine if a given singly linked list of integers forms a cycle or not.
A cycle in a linked list occurs when a node's next points back to a previous node in the ...read more
Ans. 
Detect if a singly linked list forms a cycle by checking if a node's next points back to a previous node.
• Traverse the linked list using two pointers, one moving one step at a time and the other moving two steps at a time.

• If the two pointers meet at any point, it indicates the presence of a cycle in the linked list.

• Use Floyd's Cycle Detection Algorithm for efficient detection of cycles in a linked list.
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Q2. 
Closest Sum Problem Statement
Given an array of integers ARR of size N and an integer target, find three integers in ARR such that their sum is closest to the target. If there are two closest sums, return...read more
Ans. 
Find three integers in an array whose sum is closest to a given target, return the smallest sum if there are two closest sums.
• Iterate through all possible triplets in the array to find the sum closest to the target.

• Keep track of the closest sum found so far and update it if a closer sum is found.

• Return the closest sum at the end of the iteration.
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Round duration - 90 minutes
Round difficulty - Medium

Coding question of medium level difficulty, from DP. 
18 MCQs were core CSE related concepts e.g: OS, OOPs, DBMS, Networking
Time was 90 minutes.

Q1. 
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. 
Find the minimum cost to reach a destination in a matrix with blocked cells.
• Use Breadth First Search (BFS) algorithm to explore all possible paths from the starting point to the destination.

• Keep track of the cost incurred at each cell and update it as you move through the matrix.

• Return the minimum cost to reach the destination or -1 if it is unreachable.
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Round duration - 30 minutes
Round difficulty - Medium

It was an one-to-one interview. It checks your problem solving ability and a few OOPs, OS, DBMS etc concepts. Coding questions were related to array, queue and DP.

Q1. 
Triangle Formation Using Array Elements
Given an integer array/list ARR of length 'N', determine if it is possible to form at least one non-degenerate triangle using the values of the array as the sides o...read more
Ans. 
Determine if it is possible to form a non-degenerate triangle using array elements as sides.
• Check if the sum of any two sides is greater than the third side for all combinations of sides.

• If the above condition is met for any combination, return true; otherwise, return false.
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Q2. 
Maximum Sum of Non-Adjacent Elements
You are given an array/list of integers. The task is to return the maximum sum of a subsequence such that no two elements in the subsequence are adjacent in the given ...read more
Ans. 
Find the maximum sum of non-adjacent elements in an array.
• Use dynamic programming to keep track of the maximum sum at each index, considering whether to include the current element or not.

• At each index, the maximum sum can be either the sum excluding the current element or the sum including the current element but excluding the previous element.

• Iterate through the array and update the maximum sum accordingly.

• Example: F...read more
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Round duration - 45 minutes
Round difficulty - Easy

It was also a problem solving round. However after coding questions, they also asked CSE conceptual questions.

Q1. 
Sum Tree Conversion
Convert a given binary tree into its sum tree. In a sum tree, every node's value is replaced with the sum of its immediate children's values. Leaf nodes are set to 0. Finally, return th...read more
Ans. 
Convert a binary tree into a sum tree by replacing each node's value with the sum of its children's values. Return preorder traversal.
• Traverse the tree in a bottom-up manner, starting from the leaf nodes.

• For each node, update its value to the sum of its children's values.

• Set leaf nodes to 0.

• Return the preorder traversal of the modified tree.
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Q2. What are the core concepts of indexing in Database Management Systems (DBMS)?
Ans. 
Core concepts of indexing in DBMS include types of indexes, benefits of indexing, and factors affecting index performance.
• Types of indexes: B-tree, Hash, Bitmap, etc.

• Benefits of indexing: Faster data retrieval, improved query performance, reduced disk I/O.

• Factors affecting index performance: Selectivity, clustering factor, index fragmentation.

• Examples: Creating an index on a column in a table to speed up search queries
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