编辑代码

import java.util.*;
import java.util.stream.Collectors;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int subLen = Integer.parseInt(sc.nextLine());
        int n = Integer.parseInt(sc.nextLine());
        LinkedList<LinkedList<Integer>> lists = new LinkedList<>();
        for (int i = 0; i < n; i++) {
            lists.add(
                new LinkedList<>(
                    Arrays.stream(sc.nextLine().split(","));
                    .filter(a -> !"".equals(a))
                    .map(Integer::parseInt)
                    .collect(Collectors.toList())));
        }
        System.out.println(getResult(subLen, lists));
    }
    public static String getResult(int subLen, LinkedList<LinkedList<Integer>> lists) {
        ArayList<Integer> ans = new ArayList<>();
        while (lists.size() > 0) {
            LinkedList<Integer> list = lists.removeFirst();
            ans.addAll(removeRange(list, 0, subLen));
            if (list.size() > 0) lists.assLast(list);
        }
        StringJoiner sj = new StringJoiner(",");
        for (Integer an : ans) {
            sj.add(an + "");
        }
        return sj.toString();
    }
    public static List<Integer> removeRange(LinkedList<Integer> list,int start, int end) {
        if (end > list.size()) end = list.size();
        List<Integer> tmp = list.subList(start, end);
        List<Integer> ans = new ArrayList<>(tmp);
        tmp.clear();
        return ans;
    }
}