1058 N的阶乘的长度

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 #define pi 3.1415926535
 5 #define e 2.718281828459
 6 
 7 inline int read()
 8 {
 9     char ch=getchar();
10     int k=0;
11     while (ch<‘0‘ || ch>‘9‘) {
12         ch=getchar();
13     }
14     while (ch>=‘0‘&&ch<=‘9‘) k=k*10+(ch^48),ch=getchar();
15     return k;
16 }
17 
18 int main()
19 {
20     int n;
21     n=read();
22     int m=0.5*log10(2*n*pi)+n*log10(n/e)+1;
23     printf("%d",m); 
24     return 0;
25 }