[Java]广义表

package glist;

import java.util.List;
import java.util.Scanner;

public class GList {
    static Scanner sc = new Scanner(System.in);

    public static ListNote createGList() {
        Note head = new Note();
        Note t = head;
       while (true) {
           int flag = sc.nextInt();
           if (flag == 0) {   //原子节点
               int data = sc.nextInt();
               IntNote p = new IntNote();
               p.flag = 0;
               p.data = data;
               p.pre = t;
               t.next = p;
               t = p;
           } else if (flag == 1) {
               ListNote p = createGList();
               p.pre = t;
               t.next = p;
               t = p;
           } else {
               t.next = null;
               break;
           }
       }
       head.next.pre = null;
       ListNote gList = new ListNote();
       gList.flag = 1;
       gList.gList = head.next;
       return gList;
    }
    public static void show(ListNote gList) {
        System.out.print("(");
        Note p = gList.gList;
        while (p != null) {
            if (p.flag == 0) {
                IntNote t = (IntNote)p;
                System.out.print(t.data);
            } else {
                ListNote t = (ListNote)p;
                show(t);
            }
            if (p.next != null) {
                System.out.print(",");
            }
            p = p.next;
        }
        System.out.print(")");
    }
    public static int depth(Note gList) {
        if (gList == null) return 1;
        if (gList.flag == 0) return 0;
        int max = 0;
        Note p = ((ListNote)gList).gList;
        while (p != null) {
            int tem = depth(p);
            if (tem > max) {
                max = tem;
            }
            p = p.next;
        }
        return max + 1;
    }
    public static void main(String[] args) {
        ListNote gList = createGList();
        show(gList);
        System.out.print(depth(gList));
    }
}

class Note {
    Integer flag = null;
    Note pre = null, next = null;
}
class IntNote extends Note{
    Integer data;
}
class ListNote extends Note {
    Note gList = null;
}