hdu 4061 福州赛区网络赛A 数学 ***

a1/sum

 #include<cstdio>
 #include<iostream>
 #include<algorithm>
 #include<cstring>
 #include<cmath>
 #include<queue>
 #include<map>
 using namespace std;
 #define MOD 1000000007
 const int INF=0x3f3f3f3f;
 const double eps=1e-;
 typedef long long ll;
 #define cl(a) memset(a,0,sizeof(a))
 #define ts printf("*****\n");
 const int MAXN=;
 int n,m,tt;
 int a[MAXN];
 int main()
 {
     int i,j,k,ca=;
     #ifndef ONLINE_JUDGE
     freopen("1.in","r",stdin);
     #endif
     scanf("%d",&tt);
     while(tt--)
     {
         cin>>n;
         int w,sum=;
         printf("Case %d: ",ca++);
         for(i=;i<n;i++)
         {
             int a;
             scanf("%d",&a);
             if(i==)    w=a;
             sum+=a;
         }
         printf("%.6lf\n",(double)w/sum);
     }
 }