UVA 540 Team Queue(queue的使用)

小灰灰 2022-06-08 14:17 191阅读 0赞

Queues and Priority Queues are data structures which are known to most computer scientists. The Team Queue, however, is not so well known, though it occurs often in everyday life. At lunch time the queue in front of the Mensa is a team queue, for example.

In a team queue each element belongs to a team. If an element enters the queue, it first searches the queue from head to tail to check if some of its teammates (elements of the same team) are already in the queue. If yes, it enters the queue right behind them. If not, it enters the queue at the tail and becomes the new last element (bad luck). Dequeuing is done like in normal queues: elements are processed from head to tail in the order they appear in the team queue.

Your task is to write a program that simulates such a team queue.

### Input ###

The input file will contain one or more test cases. Each test case begins with the number of teams t (  1≤t≤1000). Then t team descriptions follow, each one consisting of the number of elements belonging to the team and the elements themselves. Elements are integers in the range 0 - 999999. A team may consist of up to 1000 elements.  
Finally, a list of commands follows. There are three different kinds of commands:  
ENQUEUE x - enter element x into the team queue  
DEQUEUE - process the first element and remove it from the queue  
STOP - end of test case  
The input will be terminated by a value of 0 for t.

Warning: A test case may contain up to 200000 (two hundred thousand) commands, so the implementation of the team queue should be efficient: both enqueing and dequeuing of an element should only take constant time.

### Output ###

For each test case, first print a line saying “ Scenario \#k”, where k is the number of the test case. Then, for each DEQUEUE command, print the element which is dequeued on a single line. Print a blank line after each test case, even after the last one.  
Sample Input  
2  
3 101 102 103  
3 201 202 203  
ENQUEUE 101  
ENQUEUE 201  
ENQUEUE 102  
ENQUEUE 202  
ENQUEUE 103  
ENQUEUE 203  
DEQUEUE  
DEQUEUE  
DEQUEUE  
DEQUEUE  
DEQUEUE  
DEQUEUE  
STOP  
2  
5 259001 259002 259003 259004 259005  
6 260001 260002 260003 260004 260005 260006  
ENQUEUE 259001  
ENQUEUE 260001  
ENQUEUE 259002  
ENQUEUE 259003  
ENQUEUE 259004  
ENQUEUE 259005  
DEQUEUE  
DEQUEUE  
ENQUEUE 260002  
ENQUEUE 260003  
DEQUEUE  
DEQUEUE  
DEQUEUE  
DEQUEUE  
STOP  
0  
Sample Output  
Scenario \#1  
101  
102  
103  
201  
202  
203

Scenario \#2  
259001  
259002  
259003  
259004  
259005  
260001

code（思路见注释）：

#include <iostream>
    #include <algorithm>
    #include <cstdlib>
    #include <map>
    #include <queue>
    
    using namespace std;
    
    int main()
    {
        int t,cnt=1;
        while(cin>>t&&t)
        {
            map<int,int> IDgr;//成员p映射到他的队伍i
    
            cout<<"Scenario #"<<cnt++<<endl;
            for(int i=1;i<=t;i++)
            {
                int n,p;
                cin>>n;
                while(n--)
                {
                    cin>>p;
                    IDgr[p]=i;
                }
            }
    //队列a存已在大队伍中的各个支队伍的序号，如{1，3，2}
    //队列数组b存上面各个支队伍中的成员，而且队伍序号递增，如{103,101,102},{201},{301,303}
            queue<int> a,b[1000];
            for(;;)
            {
    
                string cmd;
                cin>>cmd;
                if(cmd[0]=='S')
                    break;
                else if(cmd[0]=='E')
                {
                    int x;
                    cin>>x;
                    int id=IDgr[x];//成员x的队伍id
                    if(b[id].empty())//该成员不在大队伍中
                        a.push(id);
                    b[id].push(x);//添加新的队伍序号
                }
                else if(cmd[0]=='D')
                {
                    int z=a.front();//首支队伍序号
                    cout<<b[z].front()<<endl;//首支队伍成员
                    b[z].pop();
    
                    if(b[z].empty())//如果首支队伍没有成员，则delete
                        a.pop();
                }
            }
            cout<<endl;
        }
        return 0;
    }