Mystery! Help (BINOFEV)

How come this code get AC but still show wrong output on sample test cases??
[https://www.codechef.com/viewsolution/28433246](Solution Link)

@just1star @ssjgz @tmwilliamlin Please look into this!

@vijju123 @anon55659401 Please help or share your views on this issue!

Is there no one who could figure out what’s the problem with this. This is a serious issue. The solution link given is of that submitted by me of BINOFEV problem, but the code is -as it is- borrowed from some candidate solution in December Long Challenge 2019.

How can it happen that solution doesn’t pass sample test cases and got AC(100) on all secret test cases.
And not only that, this is supposedly the hardest problem of the contest, and the time limit for this question is 2 s and then there is this solution which runs in 0.0 s.
:man_shrugging:

He somehow cracked the dataset. See lines 276-286 and 417-427. He basically memorized the answers for different values of r and printed them. It is actually possible to do binary search on the dataset using some asserts; he probably used some other account(s) to do that.