fzu 2037 Maximum Value Problem

http://acm.fzu.edu.cn/problem.php?pid=2037

思路：找规律，找出递推公式f[n]=f[n-1]*n+(n-1)!,另一个的结果也是一个递推，s[n]=s[n-1]+1/n;

 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #define maxn 1000010
 #define ll long long
 using namespace std;
 const int mod=;

 ll f[maxn];
 int t;
 ll n;
 ll h[maxn];
 double ans[maxn];

 void inti()
 {
     h[]=;
     h[]=;
     ans[]=1.0;
     for(int i=; i<=maxn; i++)
     {
         ans[i]=ans[i-]+1.0/i;
         h[i]=h[i-]*i;
         h[i]%=mod;
     }
     f[]=;
     for(int i=; i<=maxn; i++)
     {
          f[i]=(f[i-]*i+h[i-])%mod;
     }
 }

 int main()
 {
     inti();
     scanf("%d",&t);
     for(int cas=; cas<=t; cas++)
     {
         scanf("%lld",&n);
         printf("Case %d: %I64d %.6lf\n",cas,f[n],ans[n]);
     }
     return ;
 }