zoj 2724 Windows Message Queue（使用priority_queue容器模拟消息队列）

题目链接：

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

题目描述：

　　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 /*问题 模拟消息队列，对于每一条PUT命令，将其后的命令及参数按照优先级插入队列
2                      对于每一条GET命令，输出位于队首的消息的名称和参数，如果队列时空的输出EMPTY QUEUE!
3 插入的时候注意按优先级，如果优先级相同，按照先后次序入队即可。
4 解题思路 使用C++STL中的优先队列。识别操作，GET输出队首或者EMPTY QUEUE!，PUT进入优先队列，定义结构体比较规则*/
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;//等于的时候返回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 }