UVA 10219 - Find the ways !
Problem PDF
Solution:
#include
#include
int main()
{
long long n, r,i;
long double res;
while(scanf("%lld %lld",&n,&r)==2)
{
res = 0;
for(i=n;i>n-r;i--)
res+=log10(i);
for(i=1;i<=r;i++)
res-=log10(i);
printf("%d\n",(int)floor(res)+1);
}
return 0;
}