Zero effort
While I do think the question is on-topic for SO, I think it shows zero effort.
To demonstrate, let's take a part of the original question and reword it, just a little bit. I have replaced "algorithm" with "c# code":
So, how is this related to Stack Overflow? I want
an algorithmc# code to decide who's going to buy the croissants next week.
- The chosen person should be pseudo-random
- No one should buy the croissants twice in a row
- Generally speaking, everyone should buy croissants as many times as the others
Now the difficulty is that some of us can be absent during a week or two. Or just this Friday. And the next week, it's another. It's a company with people having vacation, and we have customers or off-days. Hence simple sorting is not good enough.
Would the changed question above be on-topic for SO? I don't think so. It sure looks like a "give me teh codez" question to me. For this reason, I voted to keep the question closed on the review queuevoted to keep the question closed on the review queue.
What Is The Precedent For Questions That Demonstrate Little Effort?
Take a look at these meta questions, about "give me teh codez":
- Can I ask a question on SO requesting somebdy to write code?
- Should I encourage questions asking for a tutorial link or code snippet?
- Am I allowed to bounty for other reasons?
I'm sure there are more. The general conclusion in the above links is that questions that show little effort are closed.