nyoj 数的长度

http://acm.nyist.net/JudgeOnline/problem.php?pid=69

#include<stdio.h>
#include<math.h>
int main()
{
    int t;
    int n;
    double sum;
    scanf("%d",&t);
    while(t--)
    {
        sum=0;
        scanf("%d",&n);
        for(int i=n;i>=1;i--)
        sum+=log10(i);
        printf("%d\n",(int)sum+1);
    }
}