题解 | #组队竞赛#

import java.util.Scanner;
import java.util.Arrays;

public class Main{
        public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        //输入n
        int n = in.nextInt();
        long[] nums = new long[3 * n];
        //输入3*n个水平值
        for(int i = 0; i < (3 * n); i++){
            nums[i] = in.nextInt();
        }
        //排成降序
        Arrays.sort(nums);
        //每组的水平值取能取到的最大值
        long sum = 0;
        int count = 0; //取值次数，一共取n次
        for(int i = nums.length - 2; count < n; i -= 2){ //nums.length-1表示最后一个元素，nums.length-2则是倒数第二个
            sum += nums[i];
            count++; //取值数+1
        }
        System.out.println(sum);
    }
}