题解 | 记负均正

import java.util.ArrayList;
import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        ArrayList<Integer> list = new ArrayList<>();
        while (in.hasNextInt()){
            int i = in.nextInt();
            for (int j = 0; j < i; j++) {
                list.add(in.nextInt());
            }
            ArrayList<Integer> list1 = new ArrayList<>();
            ArrayList<Integer> list2 = new ArrayList<>();
            for (Integer integer : list) {
                if (integer < 0){
                    list1.add(integer);
                }else if (integer > 0){
                    list2.add(integer);
                }

            }
            System.out.print(list1.size()+ " ");
            if (list2.isEmpty()){
                System.out.print("0");
            }else {
                double sum  = 0d;
                for (Integer integer : list2) {
                    sum +=  integer;
                }
                System.out.printf("%.11f", sum / list2.size() );
            }

        }

    }
}