Impact Guru PHP Interview Questions and Answers

Q1. Code postorder traversal without using recursion.
Ans. 
Iterative solution using a stack to perform postorder traversal.
• Use a stack to simulate the recursive call stack.

• Push nodes in the order of right, left, root.

• Pop nodes from stack and add to result array.

• Repeat until stack is empty.
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Q2. Leetcode Problem 1626 - Best team with no conflicts.
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Q1. Design whatsapp with one to one, group messaging and read receipts functionalities. Design the database.
Ans. 
Design a messaging app like WhatsApp with one-to-one, group messaging, and read receipts functionalities.
• Use a relational database to store user information, messages, and group memberships.

• Create tables for users, messages, groups, and group memberships.

• Include columns for message content, sender, receiver, timestamp, and read status.

• Implement a feature to mark messages as read with read receipts.

• Use indexes for effic
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Q2. Questions on dbms, cn and os.
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Asked to write different SQL queries.
1. Moving average of lf previous 10 days
2. For a data which records in and out time of an employee. How many employees were present in the office at a given time
3. A/B testing vs pre-post testing

1. Had to come up with a method to give a score to each user based on FRM(frequency, recency, monetory)
2. Guesstimate: how many burgers does McD sells in a day

Q1. Binary search for closest element
Ans. 
Binary search to find the closest element in a sorted array
• Implement binary search to find the target element in the array

• Keep track of the closest element found so far while searching

• Update the closest element if a closer one is found during the search
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Q2. String manipulation
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Q1. Low level Design for an online e-commerce website
Ans. 
Low level design for an online e-commerce website involves designing the architecture and components of the website.
• Identify the main components such as user interface, database, payment gateway, product catalog, etc.

• Design the database schema to store user information, product details, orders, etc.

• Implement user authentication and authorization mechanisms for secure access.

• Integrate payment gateway for processing tran...read more
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Q1. Coding questions medium level
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Q2. Coding questions hard
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Q1. Coding questions
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Q2. Questions related to oops, operating system,DBMS , SQL
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Q1. General questions about zepto
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Q2. Questions related to resume
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Q1. Javascript output based
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Q2. Javascript code
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Blood relation, coding and decoding, number system , percentage

Q1. LLD HLD HM rounds
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Round duration - 120 minutes
Round difficulty - Medium

Round duration - 120 minutes
Round difficulty - Medium

- Discussion on the first round's assignment
- Was asked about adding unit tests in the assignment
- Fundamental questions on the approach used for the assignment.

Q1. What are some things that could have been done better in the system design problem given in the first round?
Ans. 
Some improvements in the system design problem could include better scalability planning, more efficient data storage solutions, and improved error handling.
• Implementing a more robust caching mechanism to improve performance under heavy load.

• Optimizing the database schema for better query performance and scalability.

• Introducing load balancing and horizontal scaling to handle increased traffic.

• Enhancing error handling t...read more
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Round duration - 90 minutes
Round difficulty - Medium

Round was with tech lead. Was briefly asked about the problem I solved in the first round. Then I was asked to solve 1 medium level DSA based question. Some discussion on culture fit was also done.

Q1. Given the frequency of traffic lights' states, can you determine if there will ever be an invalid state for the traffic signal, and what are the conditions that lead to an invalid state?
Ans. 
Yes, an invalid state can occur if the traffic lights are in conflicting states simultaneously.
• An invalid state occurs when multiple traffic lights are showing conflicting signals, such as both red and green at the same time.

• This can happen due to a malfunction in the traffic light system or human error in programming the lights.

• For example, if a traffic light is stuck showing both red and green signals, it would be co
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