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.

  1 package test;
  2
  3 import java.util.HashMap;
  4 import java.util.Map;
  5
  6 public class Signboard {
  7     private Map<Integer, AD> boards;
  8
  9     public Signboard() {
 10         super();
 11         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
 12     }
 13
 14     public void rent(int begin, int end, AD ad) {
 15         for (int i = begin; i <= end; i++) {
 16             boards.put(i, ad);
 17         }
 18     }
 19
 20     public AD query(int i) {
 21         return boards.get(i);
 22     }
 23
 24     public static void main(String[] args) {
 25         Signboard signboard = new Signboard();
 26         User user = new User(1, "zhangsan", "手机号","邮箱");
 27         AD ad = new AD(1, "ad_content", user);
 28         signboard.rent(3, 5, ad);
 29         System.out.println(signboard.query(4));
 30
 31     }
 32 }
 33
 34 class User {
 35     private int id;
 36     private String name;
 37     private String tel;
 38     private String email;
 39
 40     public User() {
 41         super();
 42         // TODO Auto-generated constructor stub
 43     }
 44
 45     public User(int id, String name, String tel, String email) {
 46         super();
 47         this.id = id;
 48         this.name = name;
 49         this.tel = tel;
 50         this.email = email;
 51     }
 52
 53     public int getId() {
 54         return id;
 55     }
 56
 57     public void setId(int id) {
 58         this.id = id;
 59     }
 60
 61     public String getName() {
 62         return name;
 63     }
 64
 65     public void setName(String name) {
 66         this.name = name;
 67     }
 68
 69     public String getTel() {
 70         return tel;
 71     }
 72
 73     public void setTel(String tel) {
 74         this.tel = tel;
 75     }
 76
 77     public String getEmail() {
 78         return email;
 79     }
 80
 81     public void setEmail(String email) {
 82         this.email = email;
 83     }
 84
 85     @Override
 86     public String toString() {
 87         return "User [id=" + id + ", name=" + name + ", tel=" + tel + ", email=" + email + "]";
 88     }
 89 }
 90
 91 class AD {
 92     int id;
 93     String content;
 94     User user;//广告拥有者的引用
 95
 96     public AD() {
 97         super();
 98         // TODO Auto-generated constructor stub
 99     }
100
101     public AD(int id, String content, User user) {
102         super();
103         this.id = id;
104         this.content = content;
105         this.user = user;
106     }
107
108     public int getId() {
109         return id;
110     }
111
112     public void setId(int id) {
113         this.id = id;
114     }
115
116     public String getContent() {
117         return content;
118     }
119
120     public void setContent(String content) {
121         this.content = content;
122     }
123
124     public User getUser() {
125         return user;
126     }
127
128     public void setUser(User user) {
129         this.user = user;
130     }
131
132     @Override
133     public String toString() {
134         return "AD [id=" + id + ", content=" + content + ", user=" + user + "]";
135     }
136 }