Zenon Interview Questions, Process, and Tips

Questions were based on DSA , Databases and SQL

Library System Problem

Offline test of 3 sections, 1st aptitude, 2nd coding and 3rd dbms

Q1. 2 technical rounds. Question were about trees, sql, oops etc
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Q2. Buid a binary tree
Ans. 
A binary tree is a data structure where each node has at most two children.
• Start by creating a Node class with left and right child pointers.

• Implement methods to insert nodes, search for a specific value, and traverse the tree (inorder, preorder, postorder).

• Consider edge cases like inserting duplicate values or handling empty trees.
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Q3. Save bst to disk
Ans. 
To save a binary search tree (BST) to disk, you can serialize the tree and write it to a file.
• Serialize the BST using pre-order, in-order, or post-order traversal

• Write the serialized data to a file on disk

• When reading the data back, deserialize it to reconstruct the BST
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Q4. Sql queries, specially joins
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Q5. Infinite stream of numbers, store 10 maximum number. (Heap)
Ans. 
Use a max heap to store the 10 maximum numbers from an infinite stream of numbers.
• Implement a max heap data structure to keep track of the 10 maximum numbers.

• As new numbers come in from the infinite stream, compare them with the root of the heap.

• If the new number is greater than the root, replace the root with the new number and heapify.

• Keep the heap size limited to 10 to store only the 10 maximum numbers.
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Q1. Write sql query
Ans. 
Write a SQL query
• Understand the requirements of the query

• Identify the tables and columns needed

• Use appropriate joins and conditions

• Test the query before executing
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Q2. Write java 8 code
Ans. 
Write Java 8 code to demonstrate array manipulation
• Use Stream API for array manipulation

• Use lambda expressions for concise code

• Use method references for cleaner code
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Q1. How pandas groupby works internally?
Ans. 
Pandas groupby function in Python is used to split data into groups based on some criteria and then apply a function to each group.
• Groupby function splits the data into groups based on the specified criteria

• It then applies a function to each group separately

• The result is a new object with the function applied to each group
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Q2. Difference between Linear and tree models
Ans. 
Linear models assume a linear relationship between variables, while tree models use a hierarchical structure of decisions.
• Linear models assume a linear relationship between input variables and output, while tree models can capture non-linear relationships.

• Linear models are simpler and easier to interpret, while tree models can handle complex interactions between variables.

• Linear models are prone to overfitting with hig...read more
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Q1. How soon can you join
Ans. 
I can join within two weeks of receiving an offer.
• I can start within two weeks of receiving an offer

• My current notice period is two weeks

• I am available to start immediately
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