Sorry if this has already been answered before, I just couldn't find the answer anywhere.

Here is the problem link https://codeforces.com/contest/534/problem/D Basically, the problem boils down to finding a correct rearrangement of some numbers such that each next number is the previous number + 1 — 3m where m is some non-negative integer, and you have to start with 0. The solution is to always pick the biggest number possible, (so if you are currently on x, you try x + 1, then x — 2, then x — 5, etc...). Why does the greedy method work?

Basically what the title says. Yesterday I took part in #668 Div 2, did ok but sadly still lost a little bit of rating :(. The contest showed up on my page yesterday. Today I log on and the contest is gone from my user page. Is there a reason for this? I am a bit new to codeforces contests and I am not sure how they all work for sure so I am just wondering if this is a bug or feature.