题解 | #数据分类处理#

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;

// 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);
        Map<Integer, List<int[]>> sequence2 = new TreeMap<>();
        int[] sequence1 = null;
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int a = in.nextInt();
            sequence1 = new int[a];
            for (int i = 0; i < a ; i++) {
                sequence1[i] = in.nextInt();
            }
            int b = in.nextInt();
            for (int i = 0; i < b ; i++) {
                sequence2.put(in.nextInt(), new ArrayList<>());
            }
        }
        for (int i = 0 ; i < sequence1.length ; i ++) {
            final String sequence = sequence1[i] + "" ;
            final int i1 = i ;
            sequence2.forEach((key, value) -> {
                if (sequence.contains(key + "")) {
                    value.add(new int[] {i1, Integer.parseInt(sequence)});
                }
            });
        };
        List<Integer> sq = new ArrayList<>() ;
        sequence2.forEach((key, value) -> {
            if (value.size() > 0) {
                sq.add(key);
                sq.add(value.size());
                value.forEach(s -> {
                    sq.add(s[0]);
                    sq.add(s[1]);
                });
            }
        });
        System.out.printf(sq.size() + " ");
        sq.forEach(ss ->System.out.print(ss + " "));

    }
}