Impact Guru Backend Developer Interview Questions and Answers

Given two soted arrays merge them from a single sorted array with all items in non-decreassing order

Q1. How do you setup a Dark Store?
Ans. 
Setting up a Dark Store involves converting a retail store into a fulfillment center for online orders.
• Select a suitable location for the Dark Store, preferably in a centralized area with good access to transportation.

• Optimize the layout of the store for efficient picking, packing, and shipping of orders.

• Implement inventory management systems to track stock levels accurately and prevent stockouts.

• Train staff on order f...read more
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Q2. How do joins work in the simplest manner?
Ans. 
Joins combine data from two or more tables based on a related column.
• Joins are used to retrieve data from multiple tables based on a related column

• Common types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN

• Example: SELECT * FROM table1 INNER JOIN table2 ON table1.id = table2.id
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Q3. Write a basic query explaining the order of execution?
Ans. 
The order of execution in a query determines the sequence in which operations are performed.
• 1. The order of execution in a query typically follows the sequence: FROM, WHERE, GROUP BY, HAVING, SELECT, ORDER BY.

• 2. The FROM clause specifies the tables involved in the query.

• 3. The WHERE clause filters the rows based on specified conditions.

• 4. The GROUP BY clause groups the rows that have the same values into summary rows.

• 5...read more
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Q4. Difference between Group By and Distinct?
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Group By is used to aggregate data based on a specific column, while Distinct is used to remove duplicate rows from a result set.
• Group By is used with aggregate functions like COUNT, SUM, AVG, etc.

• Distinct is used to retrieve unique values from a column or set of columns.

• Group By can be used to group data based on multiple columns, while Distinct operates on individual columns only.
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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
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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