題目鏈接：

　　http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=2724

題目描述：

　　Message queue is the basic fundamental of windows system. For each process, the system maintains a message queue. If something happens to this process, such as mouse click, text change, the system will add a message to the queue. Meanwhile, the process will do a loop for getting message from the queue according to the priority value if it is not empty. Note that the less priority value means the higher priority. In this problem, you are asked to simulate the message queue for putting messages to and getting message from the message queue.

Input

There‘s only one test case in the input. Each line is a command, "GET" or "PUT", which means getting message or putting message. If the command is "PUT", there‘re one string means the message name and two integer means the parameter and priority followed by. There will be at most 60000 command. Note that one message can appear twice or more and if two messages have the same priority, the one comes first will be processed first.(i.e., FIFO for the same priority.) Process to the end-of-file.

Output

For each "GET" command, output the command getting from the message queue with the name and parameter in one line. If there‘s no message in the queue, output "EMPTY QUEUE!". There‘s no output for "PUT" command.

Sample Input

GET
PUT msg1 10 5
PUT msg2 10 4
GET
GET
GET

Sample Output

EMPTY QUEUE!
msg2 10
msg1 10
EMPTY QUEUE!

 1 /*問題 模擬消息隊列，對於每一條PUT命令，將其後的命令及參數按照優先級插入隊列
 2                      對於每一條GET命令，輸出位於隊首的消息的名稱和參數，如果隊列時空的輸出EMPTY QUEUE!
 3 插入的時候註意按優先級，如果優先級相同，按照先後次序入隊即可。
 4 解題思路 使用C++STL中的優先隊列。識別操作，GET輸出隊首或者EMPTY QUEUE!，PUT進入優先隊列，定義結構體比較規則*/
 5 #include <cstdio>
 6 #include <queue>
 7 #include <cstring>
 8 using namespace std;
 9 
10 struct info{
11     char name[50];
12     int para;
13     int rank;
14     bool operator < (const info &a) const{
15             return a.rank < rank;//等於的時候返回0 
16     }
17 };
18 
19 int main()
20 {
21     char op[5];
22     priority_queue<info> pq;
23     info temp;
24     while(scanf("%s",op) != EOF){
25         if(strcmp(op,"GET") == 0)
26         {
27             if(pq.empty())//空
28             {
29                 printf("EMPTY QUEUE!\n"); 
30             } 
31             else//非空
32             {
33                 printf("%s %d\n",pq.top().name,pq.top().para);
34                 pq.pop();    
35             } 
36         }
37         if(strcmp(op,"PUT") == 0)
38         {
39             scanf("%s %d %d",temp.name,&temp.para,&temp.rank);
40             pq.push(temp);
41         }
42     }    
43 } 

zoj 2724 Windows Message Queue（使用priority_queue容器模擬消息隊列）