HDOJ1509 Windows Message Queue（优先队列）

Windows Message Queue

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 2264    Accepted Submission(s): 884

Problem Description

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!

 

Author

ZHOU, Ran

 

Source

Zhejiang University Local Contest 2006, Preliminary

 

#include <cstdio>
#include <iostream>
#include <queue>

using namespace std;

struct msg
{
    char name[100];
    int parameter;
    int priority;
    int id;
    // 属性priority越小，实际优先级越大，排在队列前边
    bool operator < (const msg &p) const //注意优先队列是基于堆排序的，是不稳定排序，所以当优先级相同时不是
    {                                   //基于FIFO的，所以加一个ID属性，对于优先级相同的按照FIFO出队
        if(priority != p.priority)
            return priority > p.priority;
        return id > p.id;
    }
};
priority_queue<msg> q;

int main()
{
    char cmd[5];
    msg t1;
    int order = 0;
    while(~scanf("%s", cmd))
    {
        if(cmd[0] == 'P')
        {
            scanf("%s%d%d", t1.name, &t1.parameter, &t1.priority);
            t1.id = ++order;
            q.push(t1);
        }
        else
        {
            if(q.empty())
                printf("EMPTY QUEUE!\n");
            else
            {
                t1 = q.top();
                q.pop();
                printf("%s %d\n", t1.name, t1.parameter);
            }
        }
    }
    return 0;
}