双链表java

import java.util.Scanner;
public class Main{
    static int  idx = 0;//表示当前用到第几个了
    static int  head = -1; //头节点
    static int[]  ne = new int[100010];
    static int[] pre = new int[100010];
    static int[] e  = new int[100010];
    public static void init(){
        //idx 0 为头节点
        //idx 1 为尾节点
        ne[0]=1;
        ne[1] = 0;
        idx = 2;

    }
    public static void main(String[] args){
        init();
        Scanner sc = new Scanner(System.in);
        int count = sc.nextInt();
        while(count-->0){
            String op = sc.next();
            if(op.equals("R")){
                int val = sc.nextInt();
                insertR(pre[1],val);
            }else if(op.equals("L")){

                int val = sc.nextInt();
                insertR(0,val);
            }else if(op.equals("D")){
                int k = sc.nextInt();
                delete(k+1);
            }else if(op.equals("IL")){
                int k = sc.nextInt();
                int val = sc.nextInt();
                insertR(pre[k+1],val);
            }else if(op.equals("IR")){
                int k = sc.nextInt();
                int val  = sc.nextInt();
                insertR(k+1,val);
            }

        }
        int index = ne[0];
        while(index!=1){
            System.out.print(e[index]+" ");
            index = ne[index];
        }
    }
    public static void delete(int k ){

        ne[pre[k]] = ne[k];
        pre[ne[k]]=pre[k];
    }
    public static void insertR(int k ,int val){

        //需要做k+1
        e[idx] = val;
        ne[idx] = ne[k];
        pre[idx] = k;
        pre[ne[k]] = idx;
        ne[k]=idx;
        idx++;
    }

}