HDU1018 Big Number

题目地址：http://acm.hdu.edu.cn/showproblem.php?pid=1018<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

网上有求解的数学公式，

#include < iostream >
#include < cmath >
using namespace std;

int main()
{
intcaseNum,i,j,n,count;
doublesum;
while(cin>>caseNum)
{
for(i=0;i<caseNum;++i)
{
cin>>n;
sum=0.0f;
count=0;
for(j=1;j<=n;++j)
{
sum+=log10f(static_cast<float>(j));
}
cout<<static_cast<int>(sum)+1<<endl;
}
}
return0;
}