数字位数

给你一个数字（例如n！）求这个数字的位数。
1.log（1*2*3*4……)=log(1)+log(2)+log(3)….

#include"cstring"
#include"cstdio"
#include"iostream"
#include"cmath"
using namespace std;
int main()
{
    int n,t,i;
    double s;
    scanf("%d",&t);
    while(t--){
        scanf("%d",&n);
        s=1;
        for(i=1;i<=n;i++){
            s+=log10(i);
        }
        printf("%.0lf\n",floor(s));
    }
}

2.s=log10(2*PI*n)/2+n*log10(n/E)+1;

#include"cstring"
#include"cstdio"
#include"iostream"
#include"cmath"
using namespace std;
#define PI 3.141592654
#define E 2.71828182846

int main()
{
    int n,t,i;
    scanf("%d",&t);
    while(t--){
        scanf("%d",&n);
        long long s=1;
        if(n>3)
            s=log10(2*PI*n)/2+n*log10(n/E)+1;
        printf("%lld\n",s);
    }
}