Pixis Software Developer Interview Questions and Answers for Experienced

Round duration - 60 Minutes
Round difficulty - Easy

Q1. 
Level Order Traversal Problem Statement
Given a binary tree of integers, return the level order traversal of the binary tree.
Input:
The first line contains an integer 'T', representing the number of te...read more
Ans. 
Return the level order traversal of a binary tree given in level order with null nodes represented by -1.
• Create a queue to store nodes for level order traversal

• Start with the root node and add it to the queue

• While the queue is not empty, dequeue a node, print its value, and enqueue its children

• Repeat until all nodes are traversed in level order
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Round duration - 45 minutes
Round difficulty - Easy

Q1. What is a deadlock in DBMS, and can you explain the concepts of join and query?
Ans. 
A deadlock in DBMS occurs when two or more transactions are waiting for each other to release locks, causing them to be stuck indefinitely.
• Deadlock is a situation where two or more transactions are unable to proceed because each is waiting for the other to release locks.

• To prevent deadlocks, DBMS uses techniques like deadlock detection and prevention algorithms.

• Joins in DBMS are used to combine rows from two or more ta...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. Design a system for Twitter, outlining the key components and architecture involved.
Ans. 
Design a system for Twitter
• Key components: user profiles, tweets, hashtags, timelines

• Architecture: microservices, load balancers, databases, caching

• Scalability: sharding, replication, CDN

• Real-time processing: streaming APIs, push notifications
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Maximum Subarray Sum Queries
You are provided with an array of ‘N’ integers and ‘Q’ queries. Each query requires calculating the maximum subarray sum in a specified range of the array.
Input:
The first ...read more
Ans. 
Implement a function to calculate maximum subarray sum queries in a given range of an array.
• Iterate through each query and calculate the maximum subarray sum within the specified range using Kadane's algorithm.

• Keep track of the maximum sum found so far and update it as needed.

• Return the maximum subarray sum for each query in the test case.
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Q2. 
Sort 0 1 2 Problem Statement
Given an integer array arr of size 'N' containing only 0s, 1s, and 2s, write an algorithm to sort the array.
Input:
The first line contains an integer 'T' representing the n...read more
Ans. 
Sort an integer array containing only 0s, 1s, and 2s in linear time complexity.
• Use a single scan over the array to sort it in-place.

• Maintain three pointers for 0s, 1s, and 2s and swap elements accordingly.

• Example: Input: [0, 2, 1, 2, 0], Output: [0, 0, 1, 2, 2]
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Round duration - 20 Minutes
Round difficulty - Medium

5 verbal questions, 2 mid - hard coding on arrays, hashmap and dp

Q1. Introduce yourself and projects
Ans. 
I am a software developer with experience in web development and mobile applications.
• Developed a web application using React and Node.js for managing inventory

• Created a mobile app using Flutter for tracking daily expenses

• Familiar with Agile development practices
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Q2. Basic questions on coding define different DS and Difference btw them
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1st round is coding assessment round based on graph and hashmaps

Q1. Explain joins in SQL
Ans. 
Joins in SQL are used to combine rows from two or more tables based on a related column between them.
• Joins are used to retrieve data from multiple tables based on a related column between them

• Types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN

• INNER JOIN returns rows when there is at least one match in both tables

• LEFT JOIN returns all rows from the left table and the matched rows from the right table

• ...read more
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Q2. What are object and class in OOPs?
Ans. 
Objects are instances of classes in OOPs. Classes are blueprints for creating objects with attributes and methods.
• Objects are instances of classes

• Classes are blueprints for creating objects

• Classes define attributes and methods for objects

• Example: Class 'Car' with attributes like 'color' and methods like 'drive'
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Computer Fundamentals

Q1. Flatten a binary tree
Ans. 
Flatten a binary tree by converting it into a linked list in-place.
• Use a recursive approach to flatten the binary tree.

• Traverse the tree in a pre-order manner and keep track of the previous node.

• Set the left child of each node to null and the right child to the next node in the linked list.

• Example: Input: 1 -> 2 -> 5 -> 3 -> 4 -> null, Output: 1 -> null -> 2 -> null -> 3 -> null -> 4 -> null -> 5 -> null
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Q1. Explain hoisting in js
Ans. 
Hoisting in JavaScript is the behavior where variable and function declarations are moved to the top of their containing scope during the compilation phase.
• Variable declarations are hoisted to the top of their scope, but not their assignments.

• Function declarations are fully hoisted, meaning they can be called before they are declared.

• Hoisting can lead to unexpected behavior if not understood properly.
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Q2. Explain closures in js
Ans. 
Closures in JavaScript allow functions to access variables from their outer scope even after the outer function has finished executing.
• Closures are created when a function is defined within another function and the inner function has access to the outer function's variables.

• Closures can be used to create private variables and functions in JavaScript.

• Closures can also be used to maintain state in asynchronous operations
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Q1. Javascript polyfills
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