Invitation to CodeChef September Long Challenge 2018 sponsored by ShareChat!

Hello CodeChef Community!

We’re excited to announce the September Long Challenge sponsored by ShareChat. Along with the opportunity to boost your ratings and win some cool laddus, there are some exciting full-time job opportunities with ShareChat for professionals across the globe. More details about the job opportunities can be found on the contest page.
I hope you will join your fellow programmers and enjoy the contest problems. Joining me on the problem setting panel are:

Contest Details:

Time: 7th September 2018 (1500 hrs) to 17th September (1500 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone.).

Contest link:

Registration: You just need to have a CodeChef handle to participate. For all those, who are interested and do not have a CodeChef handle, are requested to register in order to participate.

Prizes: Top 10 performers in Global and Indian category will get CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here: First to solve each problem individually: 100 laddus (For problems common to both Divisions, only one user will get laddus for that problem).
(For those who have not yet got their previous winning, please send an email to

Good Luck!
Hope to see you participating!!


For the problem STCFOTT, the file for 3rd subtask (Single subtree) is incorrect. It passes the asserts statements I wrote for 2nd subtask (Linear tree). Please fix it.

Each Selina only changes her direction (from bouncing to falling or vice versa) when she cannot keep moving in the current direction without leaving the tree or hitting another Selina, that is, when one of the following happens:

  1. reaching a leaf when falling
  2. reaching the root when bouncing
  3. meeting another Selina that’s moving in the opposite direction

Can someone please explain me the thord condition in STCFOTT problem, preferably with an example.

I am sorry to say but the example for this problem is very poor as it does not explain any of the above conditions. I think the setter or the tester should see to such problems. Disappointed with the codechef team. @admin @mgch

1 Like

Agreed. This problem statement leaves a lot to be desired.

It seems @mcfx1 has achieved a near perfect score in the challenge problem CHEFZERO and everyone else is being awarded 0 points. Please look into it.

Not only near perfect, but perfect score, as all other users are getting exactly zero points, not something like 0.000 something.

@admin, please look into this.

Ironically name of problem CHEFZERO = Chef will give you Zero. xD.
Score of @mcfx1 0.000017 pts. His own soln with 0.642936pts fetches him zero.
We need a change in scoring fn. And rest of scores are of order 1e9.


A small change, like (max-min+1) in place of (max-min) will ensure avoidance of non zero score, though there might be some better scoring function.

1 Like

Can you please explain the third condition in a way that does not reveal the solution. I am still not able to get it completely. Thanks.

relatively his solution’s score is 10^9 times less than other’s … there’s a lot of optimization he did… great work by him… XDDDDD

there has been many challenge problem’s where bf or random answer fetches 10-50 points but this one is completely reverse of it…

Tie Breaker is a tie breaker only b/w 1st and 2nd ranks xD




@codebreaker123 I would like to, but since I am not associated with the problem setting team it is probably not my place to do so.


No response or action till now, incredible.

Seems like they updated it, now people with double digit scores are getting some points. Not big enough to be visible on ranklist page tho.

I updated the announcement when I came to know of it. Thanks to @mgch :slight_smile:

After scoring fn has been updated.

My submission page shows score of 0.046pts \approx 4.6 point on scoreboard. But it seems scoreboard is not updated. And when I visit Ranking Your Rank: 106 Your Score: 340.00002 is showing which correspond to 0.00002 pts.

Can you please check and remove conflicts.

@vijju123 how long does it take to rejudge? The scores of old submissions have not been updated yet.

Ping. xDDD