This problem is harder than the rating he has

Posted by

scythe 24 Nov 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.

Re: This problem is harder than the rating he has

Posted by

lakerka 18 May 2015 00:47

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.