Comviva Technology Interview Questions and Answers

Simple 2 leetcode easy questions, along with MCQs

Q1. Asked about implementation of linked lists,and questions about project
Ans. Implement the linked list with java
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Q2. Swap 2 variables without using a third one
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Q3. Use the XOR operator
Ans. 
XOR operator is a logical operator that returns true if and only if both operands are different.
• XOR is represented by the symbol ^

• It can be used to toggle a bit (e.g. x ^= 1)

• It can be used to check if two values are different (e.g. x ^ y)

• It can be used to encrypt and decrypt data

• It can be used to find the odd occurring element in an array
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Q1. Explain different boosting algorithm.
Ans. 
Boosting algorithms improve model accuracy by combining weak learners into a strong learner through sequential training.
• AdaBoost: Adjusts weights of misclassified instances to focus on difficult cases.

• Gradient Boosting: Optimizes a loss function by adding weak learners sequentially.

• XGBoost: An efficient implementation of gradient boosting with regularization to prevent overfitting.

• LightGBM: A gradient boosting framewor...read more
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Q2. Difference between Pandas loc and iloc
Ans. 
Pandas loc is label-based indexing, while iloc is integer-based indexing for selecting data in DataFrames.
• loc uses row and column labels for selection. Example: df.loc[0, 'column_name']

• iloc uses integer positions for selection. Example: df.iloc[0, 1]

• loc can accept boolean arrays for filtering. Example: df.loc[df['column_name'] > 10]

• iloc only accepts integer indices. Example: df.iloc[0:5] selects the first five rows.
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Q3. Write a function in python to print if a number is prime or not.
Ans. 
This function checks if a number is prime by testing divisibility from 2 to the square root of the number.
• A prime number is greater than 1 and has no divisors other than 1 and itself.

• To check if a number n is prime, test divisibility from 2 to sqrt(n).

• If n is divisible by any number in this range, it is not prime.

• Example: 5 is prime (divisors: 1, 5), while 4 is not (divisors: 1, 2, 4).
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Q4. Write a python function to print sum of subarray of any given array / list.
Ans. 
This function calculates and prints the sum of all possible subarrays of a given list.
• A subarray is a contiguous part of an array.

• The function iterates through all possible starting points of subarrays.

• For each starting point, it calculates the sum of subarrays ending at each subsequent index.

• Example: For array [1, 2, 3], subarrays are [1], [1,2], [1,2,3], [2], [2,3], [3]. Their sums are 1, 3, 6, 2, 5, 3.

• The time compl...read more
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Q5. How would you extract the highest score and corresponding subject for each student from a table containing student names, their five subjects, and scores for two consecutive years? Additionally, how would ...read more
Ans. 
Extract highest scores and calculate growth for students across subjects over two years.
• Use a data structure (like a DataFrame) to store student names, subjects, and scores.

• Group data by student and subject to find the maximum score for each subject.

• Example: If Student A has scores [80, 90, 85, 70, 95] in subjects [Math, Science, English, History, Art], the highest score is 95 in Art.

• For growth calculation, compare sco...read more
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Q6. I was being first approached for a different role and did an interview, that interview was really good. The person was good and helpful it was kind of a technical discussion about data. He asked few techni...read more
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Q1. What are the differences between the PHP functions explode and implode?
Ans. 
explode splits a string into an array, while implode joins array elements into a string.
• explode(separator, string): Splits a string by a specified separator.

• Example: explode(',', 'apple,banana,cherry') returns ['apple', 'banana', 'cherry'].

• implode(separator, array): Joins array elements into a single string with a specified separator.

• Example: implode('-', ['2023', '10', '05']) returns '2023-10-05'.

• explode is used for p...read more
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Q2. What is your knowledge and experience with PHP frameworks?
Ans. 
I have extensive experience with PHP frameworks like Laravel and CodeIgniter, focusing on building scalable web applications.
• Proficient in Laravel for its elegant syntax and robust features like Eloquent ORM and Blade templating.

• Experience with CodeIgniter for lightweight applications, emphasizing speed and simplicity.

• Utilized Symfony components in various projects for reusable libraries and better structure.

• Implemente...read more
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Q1. Add a new column to the database table in production which is already having 100 million of data
Ans. 
Use a tool like Rails migration to add a new column to the database table in production with 100 million data.
• Create a new Rails migration file to add the new column to the database table.

• Test the migration locally to ensure it works as expected.

• Deploy the migration to the production environment during a maintenance window to avoid downtime.

• Consider using tools like ActiveRecord's `change_column` method to efficiently ...read more
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Q2. How an application running in cloud with tightly coupled infrastructure can be deployed to on-premise
Ans. 
An application running in cloud with tightly coupled infrastructure can be deployed to on-premise by decoupling the components and using containerization.
• Decouple the application components to make them more portable

• Use containerization technologies like Docker to package the application and its dependencies

• Deploy the containerized application to on-premise servers using tools like Kubernetes for orchestration
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