UVA-540 Team QueueTeam QueueInputOutputSample InputSample OutputReference CodeTip

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概述

Team Queue

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

Reference Code

#include <cstdio>
#include <queue>
#include <map>
const int maxn=2e4+10;
template <typename T>
struct teamqueue{
    std::map<T,int> team;
    std::queue<T> qq,q[maxn];
    void addteam(T x,int t){
        team[x]=t;
    }
    void push(T x){
        int t=team[x];
        if (q[t].empty()) qq.push(t);
        q[t].push(x);
    }
    void pop(){
        int t=qq.front();
        printf("%dn",q[t].front());
        q[t].pop();
        if (q[t].empty()) qq.pop();
    }
};
int main(){
    int t,cnt=0;
    while (scanf("%d",&t),t){
        printf("Scenario #%dn",++cnt);
        teamqueue<int> tq;
        for (int i=1;i<=t;++i){
            int n;
            scanf("%d",&n);
            for (int j=0;j<n;++j){
                int x;
                scanf("%d",&x);
                tq.addteam(x,i);
            }
        }
        char str[10];
        while (scanf("%s",str)){
            if (str[0]=='S') break;
            else if (str[0]=='D') tq.pop();
            else{
                int x;
                scanf("%d",&x);
                tq.push(x);
            }
        }
        printf("n");
    }
    return 0;
}

Tip

水题，让模拟一个叫做team queue的队列。这个队列里面的每一个元素都属于某个team，每次push的时候都要将元素push到队列中它所在team的尾端，如果没有，就push到最后。

受到STL中双端队列的启发（在SGI STL双端队列deque的实现中，用了一个数组保存若干个指针，每个指针指向一片内存区域，这样一来就好像是维护了一大段连续内存），我们可以用原生队列封装成题目所需的team queue，用qq（queue of queue）保存team的标号在team queue中的相对位置，然后再在对应的q中存储真正的元素。