题目描述

算法1

Java 代码

import java.io.*;
import java.util.Scanner;

public class Main {
    private static int N = 100010;
    private static int[] e = new int[N];
    private static int[] ne = new int[N];
    private static int head;  
    private static int idx;

    private static void init() {
        head = -1;  
        idx = 0;    
    } 

    private static void addToHead(int val){
       e[idx] = val;
       ne[idx] = head;
       head = idx;
       idx++;
    }

    private static void remove(int k){
        ne[k] = ne[ne[k]];
    }

    private static void insert(int k, int val){
       e[idx] = val;
       ne[idx] = ne[k];
       ne[k] = idx;
       idx++;
    }

    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        int m = Integer.parseInt(reader.readLine());
        init();
        while (m-- > 0) {
            String[] s = reader.readLine().split(" ");
            if (s[0].equals("H")) { 
                int val = Integer.parseInt(s[1]);
                addToHead(val);
            } else if (s[0].equals("I")) {   
                int k = Integer.parseInt(s[1]);
                int val = Integer.parseInt(s[2]);
                insert(k-1, val);    
            } else {    
                int k = Integer.valueOf(s[1]);
                if(k==0) head = ne[head];
                else remove(k-1);
            }
        }

        for (int i = head; i != -1; i = ne[i]) {
            System.out.print(e[i] + " ");
        }
    }
}