I use java BigInteger and get WA#7
I use formula f(n,k)=f(n-1,k)+f(n-1,k-1)+...+f(n-1,k-9)
if you see it is wrong,please help

Edited by author 25.01.2009 13:43

I use the same formula as you.

and I get WA#7 too.

Do you realize that the number of such tickets can be of the order of 10^N, that is an N-digit number, where N~50 of decimal digits?

Edited by author 18.01.2009 03:51

Edited by author 18.01.2009 03:53

The formula is correct,just made a stupid bug:
I wrote
a[j][i]=a[j][i].add(a[j][l])
instead of
a[j][i]=a[j][i].add(a[j][i-l])
:)

Edited by author 25.01.2009 13:42

Edited by author 25.01.2009 13:42

I guess that the test 7 contains 50 900. The test 8 contains 50 450.