zoj 2724 Windows Message Queue

Windows Message Queue

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Time Limit: 2 Seconds      Memory Limit: 65536 KB

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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

GETPUT msg1 10 5PUT msg2 10 4GETGETGET

Sample Output

EMPTY QUEUE!msg2 10msg1 10EMPTY QUEUE! 题意 优先队列（小顶堆），输入put表示进去队列，第二个数字表示优先级，优先级值最小的优先级大，输入get之后，输出堆顶元素，若为空，输出EMPTY QUEUE!
#include<cstdio>#include<algorithm>#include<queue>#include<cstring>using namespace std;struct node{    char s[20];    int p;    int d;//记录优先级    int f;//第几个进入队列};bool operator<(const node &a,const node &b)//重载小于号{    if(a.d==b.d)        return a.f>b.f;        return a.d>b.d;//相当于greater，这是小顶堆，反之大顶堆}node cmp;int main(){    priority_queue<node>que;//默认大顶堆，堆顶元素最大   // priority_queue<int, vector<int>, less<int>> 大顶堆：表示其他都比堆顶小   //priority_queue<int, vector<int>, greater<int>> 小顶堆：表示其他都比堆顶大    char a[6];    while(scanf("%s",a)!=EOF)    {        if(a[0]=='G')        {            if(que.empty())                printf("EMPTY QUEUE!\n");            else{             cmp=que.top();//堆顶元素             que.pop();//             printf("%s %d\n",cmp.s,cmp.p);            }        }        else            if(a[0]=='P')        {            scanf("%s %d %d",&cmp.s,&cmp.p,&cmp.d);            cmp.f++;//记录第几个进入队列            que.push(cmp);        }    }    return 0;}