E[N]=2E[N-1]-H[N]

最简解法：

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        double E = 0;
        for(int i = 1; i <= N; ++i) E += sc.nextInt()*Math.pow(2, N - i);
        System.out.println((int)Math.ceil(E/Math.pow(2, N)));
    }
}