Problem Code : INVSMOD2
Hint 1
Page 7, Theorem 3 of https://cs.uwaterloo.ca/journals/JIS/VOL4/MARGOLIUS/inversions.pdf
Hint 2
TonyK comment on binomial coefficients - $C(n,p)$: even or odd? - Mathematics Stack Exchange
Special Hint
If you didn’t get the question even after visiting the above links during contest, here’s an easy Video Editorial .
PS : Stay tuned for more short editorials.
5 Likes
carre
October 12, 2020, 7:20pm
2
Short editorial? Links to a 13 pages article!
Anyway, good contribution, I also came up with Knuth’s formula through this paper
Waiting for the official editorial, looking for an alternative approach
3 Likes
Yeah, it was kind of a stumble upon situation. Also, to make it more accurate, I mentioned the theorem number as well. Would be interesting to know what’s in the official editorial.