51Nod1130斯特林近似

log10(n!)=log10(2*pi*n)*0.5+n*log10(n/e)

注意long long

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<string>
 5 #include<cmath>
 6 #define ll long long
 7 #define pi 3.1415926535
 8 #define E 2.718281828459
 9 using namespace std;
10 const int mod=1e9+7;
11 int n,x;
12 int main(){
13     cin>>n;
14     for(int i=1;i<=n;i++){
15         cin>>x;
16         double s=log10(2*pi*x)*0.5+x*(log10(x/E));
17         cout<<(long long)(s)+1<<endl;
18     }
19     return 0;
20 }

标签：pi,51Nod1130,斯特林,近似,long,int,include,log10,define
来源： https://www.cnblogs.com/sz-wcc/p/10446266.html