Sample Input43 2 4 553 5 99 32 12 Sample Output6.00000052.833333

 

分析：？？？

 

1 #include
     
       2 #include
      
        3 #include
       
         4 #include
        
          5 #include
         
           6 #include
          
            7 using namespace std; 8 9 const int maxn = 2005;10 const int N=120007;11 12 #define lson rt<<1///rt*213 #define rson rt<<1|1///rt*2+114 15 int main()16 {17 int n,i;18 int a[1200];19 20 while(scanf("%d", &n) != EOF)21 {22 int sum=0;23 for(i=1;i<=n;i++)24 scanf("%d", &a[i]);25 26 if(n==1)27 printf("%lf\n",1.0*a[1]);28 else if(n==2)29 printf("%lf\n",1.0*(a[1]+a[2])/2);30 else31 {32 for(i=2;i