Urban Company Software Developer Interview Questions and Answers for Experienced

Round duration - 60 Minutes
Round difficulty - Easy

Q1. 
0/1 Knapsack Problem Statement
A thief is planning to rob a store and can carry a maximum weight of 'W' in his knapsack. The store contains 'N' items where the ith item has a weight of 'wi' and a value of...read more
Ans. 
Yes, the 0/1 Knapsack problem can be solved using dynamic programming with a space complexity of not more than O(W).
• Use a 1D array to store the maximum value that can be stolen for each weight capacity from 0 to W.

• Iterate through each item and update the array based on whether including the item would increase the total value.

• The final value in the array at index W will be the maximum value that can be stolen.
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Q2. 
Find the Second Largest Element
Given an array or list of integers 'ARR', identify the second largest element in 'ARR'.
If a second largest element does not exist, return -1.
Example:
Input:
ARR = [2,...read more
Ans. 
Find the second largest element in an array of integers.
• Iterate through the array to find the largest and second largest elements.

• Handle cases where all elements are identical.

• Return -1 if a second largest element does not exist.
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Round duration - 60 Minutes
Round difficulty - Easy

System Design Round

Q1. Design a system for Twitter, discussing its architecture, key components, and scalability considerations.
Ans. 
Design a scalable system for Twitter with key components and architecture.
• Use microservices architecture for scalability and fault isolation.

• Key components include user service, tweet service, timeline service, and notification service.

• Use a distributed database like Cassandra for storing tweets and user data.

• Implement a message queue like Kafka for handling real-time updates and notifications.

• Use a caching layer like ...read more
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Round duration - 30 Minutes
Round difficulty - Easy

It is just a formality

3 Moderate questions were asked. I managed to solve 2 completely and 1 partially.

Q1. Question related to system design were asked.
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Q2. He asked me to design some functions of facebook.
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Q1. Introduction type questions were asked. In this it will prefer only CS students
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Round duration - 120 Minutes
Round difficulty - Medium

Machine Coding Round
2 Hours in Total
15 Mins for Question Explaination and Doubts
1.5 Hours for coding
15 mins to discuss the approach 

Timing - 3 to 5 pm (They are flexible)
Interviewer was very patient and helped me understand the question

Round duration - 60 Minutes
Round difficulty - Medium

2 Data Strucutre Questions
Timing 5-6 pm (They are flexible)
Google Meet
Online IDE

Q1. 
Unique Binary Search Trees Problem Statement
Given an integer 'N', your task is to compute the number of structurally unique BSTs (binary search trees) that can be formed using an exact number of 'N' uniq...read more
Ans. 
The task is to compute the number of structurally unique BSTs that can be formed using an exact number of unique values.
• Use dynamic programming to solve the problem efficiently.

• The number of structurally unique BSTs can be calculated using Catalan numbers.

• For N nodes, the number of structurally unique BSTs is given by the Nth Catalan number.

• Example: For N=3, the number of structurally unique BSTs is 5.
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Q2. 
Subsequences of String Problem Statement
You are provided with a string 'STR' that consists of lowercase English letters ranging from 'a' to 'z'. Your task is to determine all non-empty possible subsequen...read more
Ans. 
Generate all possible subsequences of a given string.
• Use recursion to generate all possible subsequences by including or excluding each character in the string.

• Maintain a current index to keep track of the characters being considered.

• Append the current character to each subsequence generated so far.

• Recursively call the function with the next index to include or exclude the next character.

• Base case: When the current ind...read more
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Round duration - 60 Minutes
Round difficulty - Easy

HIRING MANAGER ROUND

Discussion about the organisation now questions

Q1. Cab booking system
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Q1. It was lld question to design a cab booking system.
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Q2. Tell me about yourself
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There were 2 questions.
1. Knapsack
2. Median in an array

Q1. LLD(machine coding) of Google meet
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Q1. In depth discussion on my projects and resume
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Q1. Implementation of LRU cache
Ans. 
LRU cache is a data structure that stores the most recently used items, discarding the least recently used items when full.
• Use a doubly linked list to keep track of the order of items based on their usage.

• Use a hash map to quickly access items in the cache.

• When a new item is accessed, move it to the front of the linked list. If the cache is full, remove the item at the end of the list.
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Q2. Implementation of HashMap
Ans. 
HashMap is a data structure that stores key-value pairs and allows for fast retrieval of values based on keys.
• HashMap is implemented using an array of linked lists or a balanced tree to handle collisions.

• It uses a hash function to map keys to indices in the array.

• Example: HashMap<String, Integer> map = new HashMap<>(); map.put("key", 123); int value = map.get("key");
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3 Medium level dsa questions

Q1. Lld of cab booking system
Ans. 
The Low Level Design (LLD) of a cab booking system involves detailing the system architecture and components at a lower level of abstraction.
• Identify the main components of the system such as user interface, booking engine, payment gateway, and driver allocation algorithm.

• Define the interactions between these components and how data flows between them.

• Specify the data structures and algorithms used for efficient bookin...read more
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Q2. Discussion about online assesment
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