#include<stdio.h>
int main()
{    double x,y,sum=0,c;
    int n,i;
	scanf("%d",&n);
	scanf("%lf%lf",&x,&y);
	i=n;
    while(i)
	{
		scanf("%lf",&c);
		sum+=c*i--;
	}
	printf("%.2f\n",(y+x*n-2*sum)/(n+1));
	return 0;
}

• Re:第30题留个记号 (8) 20092134 2011-07-17 02:34:20