Atlassian's DSA rounds lean on graph and tree traversal (several candidates report lowest-common-ancestor style problems framed around an employee/department hierarchy), plus stream-processing and caching-design problems. The three problems below are real, recently reported (2025) Atlassian questions with full solutions.
A company's structure is modeled as a tree of departments, with employees attached as leaves and departments nested under other departments. Given a list of employees, find the nearest department that covers all of them. Some given employee IDs may not exist in the structure at all — your solution needs to handle that gracefully rather than assume every input employee is valid.
Input: hierarchy rooted at 'Engineering' -> { 'Platform': ['alice','bob'], 'Payments': ['carol'] }, employees = ['alice', 'carol']
Output: 'Engineering'
alice sits under Platform and carol under Payments, so the nearest department covering both is their common parent, Engineering.
Design a data structure that ingests a stream of (timestamp, price) stock updates — where an update for a timestamp you've already seen should correct the previously recorded price rather than add a duplicate — and supports querying the current (most recent timestamp's) price, the maximum price ever recorded, and the minimum price ever recorded, all efficiently.
Input: update(1, 10) -> update(2, 5) -> update(1, 3) -> current() -> maximum() -> minimum()
Output: 5, 5, 3
Correcting timestamp 1 from 10 to 3 must be reflected in both the current price (still timestamp 2's value) and the minimum, without a full rescan.
Implement a Least-Recently-Used (LRU) cache with a fixed capacity that supports get(key) and put(key, value) in O(1) time. When the cache is full and a new key is inserted, evict the least recently used entry first.
Input: capacity=2 -> put(1,1) -> put(2,2) -> get(1) -> put(3,3) -> get(2)
Output: 1, then -1
Accessing key 1 makes it most-recently-used, so inserting key 3 evicts key 2 instead of key 1.
More DSA questions Atlassian has asked recently
This topic was reported in a verified 2025 Atlassian loop. Full problem statements, solutions and explanations are part of the Placement-Ready PYQ Kit.
1 more verified DSA question with a full solution in the full Placement-Ready PYQ Kit
Includes the exact round it was asked in, from the Karat screen through onsite loops.