poj 3481 Double Queue

#include<iostream>        //随时插入数据并删除最低（高）优先级的数据
#include <map>
using namespace std;
int main()
{
    map<int,int> col;
    map<int,int>::iterator ite;
    int op,k,p;
    while(scanf("%d",&op)&&op)
    {
        if(op==1)
        {
            scanf("%d%d",&k,&p);
            col[p]=k;
        }
        else if(op==2)
        {
            if(col.empty())
                printf("0\n");
            else
            {
                ite=col.end();
                ite--;
                printf("%d\n",ite->second);
                col.erase(ite);
            }
        }
        else
        {
            if(col.empty())
                printf("0\n");
            else
            {
                ite=col.begin();
                printf("%d\n",ite->second);
                col.erase(ite);
            }
        }    
    }
    return 0;
}