I had applied on the Airbnb career portal, was contacted by an Airbnb recruiter after a couple weeks. They screen candidates through an online assessment.

Online Assesment: It was Hackerrank test, had just 1 question. It was a graph based problem. I don't remember exactly what it was. My solution gave TLE for 1 test-case and passed the remaining test-cases.

I was invitied for further rounds. There were 2 coding rounds (45 mins each) and 1 design round (about 60 mins).

Round1 (45-min): Find minimum window in a string containing all characters from a given pattern: https://leetcode.com/problems/minimum-window-substring/
I suggested a brute force approach first, with some hints I was able to come up with an optimal solution but my code had some bugs.

Round2 (45 mins): Sliding puzzle similar to this: https://leetcode.com/problems/sliding-puzzle/
I started with a DFS based approach which is sub-optimal for this question. Then moved to BFS based approach which was a better solution. The interviewer pointed out a couple of errors in my code.

Round 3 (System design, 1 hr): You are getting current weather data at periodic intervals from multiple sub-stations within a country. Each sub-station will give you the weather data for its region, they had given the format of data that the sub-stations send. Build a system to fetch historical data and also given predictions about the future weather for a given region. They wanted the high-level design. Sorry if the question seems vague, I might have forgotten some details.

Verdict: Rejected due to coding round. They expect an optimal solution with not too much hints.