Greendeck Full Stack Developer 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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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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Majorily on SQL and Databases

Q1. Align two images in a page with same width and same height
Ans. 
Use CSS to align two images with same width and height on a page
• Set both images to have the same width and height using CSS

• Use flexbox or grid layout to align the images horizontally or vertically

• Adjust margins or padding to fine-tune the alignment
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Q2. Array related question
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Q1. Situation based question
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Q2. Majorily focused on project
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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. React JS, coding round, DSA, poly phill, map , shallow copy deep copy, popular JS DSA questions
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Basic React JS clock/ stopwatch

2 coding question one on maximum sum problem and other on tree traversal

Q1. Dbms oops dsa questions are there and one coding question which you have to pseudo code it and dry run it
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3D DP, DP ON BST, Focus on highlevel dp and system design

Q1. LRU Cache - how to tackle
Ans. 
LRU Cache is a data structure that maintains a list of items in order of most recently used to least recently used.
• Implement using a doubly linked list and a hashmap for efficient operations

• When an item is accessed, move it to the front of the list

• When the cache is full, remove the least recently used item from the end of the list
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Q2. LRU Cache implementation based on a real time system. How would the main work which will be called etc etc
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