网易的一道笔试题的参考解法---关于广告牌投放问题

    有N个广告牌(N<=10万)可以投放广告,有k个用户(k<10亿)在这些广告牌上投放广告.操作rent(i,j,k)将从i到j块广告牌展示用户k的广告,如果原来有别的广告就覆盖掉. 操作query(i)返回第i个广告牌上现在投放的是哪个广告. rent和query操作出现的频率相等.要求设计一个数据结构和相应的算法,尽可能快的实现这两种操作.

package test;

import java.util.HashMap;
import java.util.Map;

public class Signboard {
    private Map<Integer, AD> boards;

    public Signboard() {
        super();
        boards = new HashMap<Integer, AD>();//Integer参数记录广告牌的位置，AD参数记录广告内容
    }

    public void rent(int begin, int end, AD ad) {
        for (int i = begin; i <= end; i++) {
            boards.put(i, ad);
        }
    }

    public AD query(int i) {
        return boards.get(i);
    }

    public static void main(String[] args) {
        Signboard signboard = new Signboard();
        User user = new User(1, "zhangsan", "手机号","邮箱");
        AD ad = new AD(1, "ad_content", user);
        signboard.rent(3, 5, ad);
        System.out.println(signboard.query(4));

    }
}

class User {
    private int id;
    private String name;
    private String tel;
    private String email;

    public User() {
        super();
        // TODO Auto-generated constructor stub
    }

    public User(int id, String name, String tel, String email) {
        super();
        this.id = id;
        this.name = name;
        this.tel = tel;
        this.email = email;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getTel() {
        return tel;
    }

    public void setTel(String tel) {
        this.tel = tel;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", tel=" + tel + ", email=" + email + "]";
    }
}

class AD {
    int id;
    String content;
    User user;//广告拥有者的引用

    public AD() {
        super();
        // TODO Auto-generated constructor stub
    }

    public AD(int id, String content, User user) {
        super();
        this.id = id;
        this.content = content;
        this.user = user;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    @Override
    public String toString() {
        return "AD [id=" + id + ", content=" + content + ", user=" + user + "]";
    }
}