Porter Senior Software Development Engineer Interview Questions and Answers

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

Data Structures, Coding MCQs

Q1. What is Data Structure
Ans. 
Data structures are organized formats for storing, managing, and accessing data efficiently.
• 1. Types: Common data structures include arrays, linked lists, stacks, queues, trees, and graphs.

• 2. Arrays: Fixed-size collections of elements, e.g., [1, 2, 3, 4].

• 3. Linked Lists: Collections of nodes where each node points to the next, e.g., 1 -> 2 -> 3.

• 4. Stacks: Last-in, first-out (LIFO) structures, e.g., function call ...read more
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Q2. Write DFS Algorithm
Ans. 
Depth-First Search (DFS) is a graph traversal algorithm that explores as far as possible along each branch before backtracking.
• DFS uses a stack data structure, either explicitly or via recursion.

• It starts from a selected node and explores each branch before backtracking.

• Example: In a binary tree, DFS can be implemented using pre-order, in-order, or post-order traversal.

• DFS can be used to find connected components in a ...read more
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Easy level to Medium level

2 Easy questions of DSA

Q1. One DSA question
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Q2. Normal discussion about tech stack
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Q1. Tell about yourself
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Q2. Why do you want to join digit?
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Q1. Create a controller , service and repository methods and classes to save userDeatils in table using Spring Data JPA .
Ans. 
Create a controller, service, and repository to save user details using Spring Data JPA.
• Create a UserController class with appropriate mappings for saving user details.

• Create a UserService class with a method to save user details.

• Create a UserRepository interface that extends JpaRepository to handle database operations.

• Implement the saveUserDetails method in the UserService class to call the save method of the UserRepo...read more
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Questions were crayon box ,the bot and the game and happy neighbourhood for 90 mins

Q1. Array basics was asked
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Q2. Segment tree,prefix sum
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Q1. Low level design was asked
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Q1. Stock buy and sell with at most 2 transaction
Ans. 
Implement a solution to find the maximum profit from buying and selling stocks with at most 2 transactions.
• Use dynamic programming to keep track of maximum profit at each day with 0, 1, or 2 transactions.

• Consider the possibility of splitting the transactions into two separate parts.

• Calculate the maximum profit by iterating through the prices array and updating the maximum profit accordingly.
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Q2. Binary search to find target
Ans. 
Binary search is a divide and conquer algorithm that efficiently finds a target value in a sorted array.
• Divide the array in half and compare the target value with the middle element

• If the target is less than the middle element, search the left half. If greater, search the right half

• Repeat the process until the target is found or the subarray is empty
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Q1. General about project
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Q2. Design paytm wallet
Ans. 
Design a digital wallet system similar to Paytm.
• Allow users to add money to their wallet using various payment methods like credit/debit cards, net banking, UPI, etc.

• Enable users to make payments for various services like mobile recharge, bill payments, online shopping, etc.

• Implement security measures like two-factor authentication, encryption of sensitive data, and regular security audits.

• Provide features like transac...read more
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Q1. What is thread ?
Ans. 
A thread is a lightweight process that can run concurrently with other threads within the same process.
• Threads allow for parallel execution of tasks within a single process.

• Threads share the same memory space and resources of the process they belong to.

• Threads can communicate with each other through shared memory or message passing.

• Examples: Java threads, POSIX threads (pthreads) in C/C++.
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Q2. Inter process communication and project?
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Seat reservation system
bit manipulation
binary tree related

Q1. Bfs / dfs traversal question
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