Atlassian Principal Software Engineer Interview Questions and Answers

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