hdu 2086

PS:推算。。。数组如果开得不够大也会超时。。。

代码:

#include "stdio.h"
double cal(int t,double a[]);
int main(){
    double a0,an1,c[],sum,k;
    int i,n,b;
    while(~scanf("%d",&n)){
        scanf("%lf%lf",&a0,&an1);
        for(i=;i<=n;i++)
            scanf("%lf",&c[i]);
        sum=(double)n/(double)(n+)*a0+1.0/(n+)*an1;
        k=(double)n*2.0;
        for(i=;i<=n;i++){
            sum-=k/(n+)*c[i];
            k-=2.0;
        }
        printf("%.2lf\n",sum);
    }
    return ;
}