求N!的长度【数学】 51nod 1058 1130

#include <bits/stdc++.h>
using namespace std;
int main() {
int n;
cin >> n;
double ans = 1;
for(int i = 1; i <= n; i++) {
ans += log10(i);
}
cout << (int)ans << endl;
}

#include <bits/stdc++.h>
#define PI 3.1415926535898
#define e 2.718281828459
using namespace std;
int main() {
int T, n;
cin >> T;
while(T--) {
cin >> n;
double ans = log10(sqrt(2.0*PI*n)) + n*log10(n*1.0/e);// pow(n*1.0/e, n);
cout << (long long)ans + 1 << endl;
}
}