Обсуждение @ 1091. Тмутараканские экзамены @ Timus Online Judge

scythe This problem is harder than the rating he has [1] // Задача 1091. Тмутараканские экзамены 24 ноя 2011 01:52

some hints:
use pascal triangle to generate c(n,k) if you use 63 bits data type all will fit.
prime factorize each number
for each prime count the number of number where he is a factor
calculate number of posibilites
remove duplicates ( this is what makes this problem a little bit harder ).

Good luck.

lakerka Re: This problem is harder than the rating he has // Задача 1091. Тмутараканские экзамены 18 май 2015 00:47

scythe писал(a) 24 ноября 2011 01:52

remove duplicates ( this is what makes this problem a little bit harder ).

If you don't know how to do this part take a look at derivation of Euler's totient function.

Обсуждение задачи 1091. Тмутараканские экзамены