POJ2585 Window Pains 拓扑排序

Window Pains

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 1843		Accepted: 919

Description

Boudreaux likes to multitask, especially when it comes to using his computer. Never satisfied with just running one application at a time, he usually runs nine applications, each in its own window. Due to limited screen real estate, he overlaps these windows and brings whatever window he currently needs to work with to the foreground. If his screen were a 4 x 4 grid of squares, each of Boudreaux's windows would be represented by the following 2 x 2 windows: 

1	1	.	.
1	1	.	.
.	.	.	.
.	.	.	.

.	2	2	.
.	2	2	.
.	.	.	.
.	.	.	.

.	.	3	3
.	.	3	3
.	.	.	.
.	.	.	.

.	.	.	.
4	4	.	.
4	4	.	.
.	.	.	.

.	.	.	.
.	5	5	.
.	5	5	.
.	.	.	.

.	.	.	.
.	.	6	6
.	.	6	6
.	.	.	.

.	.	.	.
.	.	.	.
7	7	.	.
7	7	.	.

.	.	.	.
.	.	.	.
.	8	8	.
.	8	8	.

.	.	.	.
.	.	.	.
.	.	9	9
.	.	9	9

When Boudreaux brings a window to the foreground, all of its squares come to the top, overlapping any squares it shares with other windows. For example, if window 1and then window 2 were brought to the foreground, the resulting representation would be:

1	2	2	?
1	2	2	?
?	?	?	?
?	?	?	?

If window 4 were then brought to the foreground:

1	2	2	?
4	4	2	?
4	4	?	?
?	?	?	?

. . . and so on . . . 
Unfortunately, Boudreaux's computer is very unreliable and crashes often. He could easily tell if a crash occurred by looking at the windows and seeing a graphical representation that should not occur if windows were being brought to the foreground correctly. And this is where you come in . . .

Input

Input to this problem will consist of a (non-empty) series of up to 100 data sets. Each data set will be formatted according to the following description, and there will be no blank lines separating data sets.

A single data set has 3 components: 

1. Start line - A single line: 
   START 
   
   
2. Screen Shot - Four lines that represent the current graphical representation of the windows on Boudreaux's screen. Each position in this 4 x 4 matrix will represent the current piece of window showing in each square. To make input easier, the list of numbers on each line will be delimited by a single space. 
3. End line - A single line: 
   END 

After the last data set, there will be a single line: 
ENDOFINPUT 

Note that each piece of visible window will appear only in screen areas where the window could appear when brought to the front. For instance, a 1 can only appear in the top left quadrant.

Output

For each data set, there will be exactly one line of output. If there exists a sequence of bringing windows to the foreground that would result in the graphical representation of the windows on Boudreaux's screen, the output will be a single line with the statement: 

THESE WINDOWS ARE CLEAN 

Otherwise, the output will be a single line with the statement: 
THESE WINDOWS ARE BROKEN 

Sample Input

START
1 2 3 3
4 5 6 6
7 8 9 9
7 8 9 9
END
START
1 1 3 3
4 1 3 3
7 7 9 9
7 7 9 9
END
ENDOFINPUT

Sample Output

THESE WINDOWS ARE CLEAN
THESE WINDOWS ARE BROKEN

题目链接：http://poj.org/problem?id=2585

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题意：
有一个拥有4×4网格的显示屏，有9个2×2的程序窗口，把一个窗口调到最前时，它的所有方格中的数字都位于最前，覆盖共用的方格。按照不同的顺序将窗口调到最前，但是计算机很不稳定，经常崩溃。输入的窗口的状态，判断是否能出现这样的窗口状态。可以的话说明计算机没有崩溃，输出“THESE WINDOWS ARE CLEAN”，否则输出“THESE WINDOWS ARE BROKEN”。
每组数据已“START”开始，已“END”结束。中间是方格数字显现的状态。如果输入“ENDOFINPUT”就结束输入。

计算机每个方格中拥有的数字：

1	1,2，	2,3，	3
1,4	1,2,4,5	2,3,5,6	3,6
4	4,5	5,6,8,9	6,9
7	7,8	8,9	9

那么相应方格中显示出来的数字就覆盖了相应方格中那些其他的数字。覆盖之间建立一条边，最终形成的图是否正常。

这就是一个拓扑排序问题，图中不能有环，有环说明不合理，也就是计算机崩溃。无环说明图合理。

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int L[10][10];
int indegree[10];
int TopSort();
int main()
{
    int i,j,t;
    string cover[5][5];
    for(i=0; i<3; i++)
    {
        for(j=0; j<3; j++)
        {
            cover[i][j]+=j+1+i*3+'0';
            cover[i][j+1]+=j+1+i*3+'0';
            cover[i+1][j]+=j+1+i*3+'0';
            cover[i+1][j+1]+=j+1+i*3+'0';
        }
    }
    /**
    for(i=0; i<4; i++)
    {
        for(j=0; j<4; j++)
        {
            string::iterator y;
            for (y=cover[i][j].begin(); y!=cover[i][j].end(); ++y)
            {
                cout<<*y;
            }
            cout<<" ";
        }
        cout<<endl;
    }
    */
    string s;
    while(cin>>s)
    {
        getchar();
        if(s=="ENDOFINPUT") break;
        memset(indegree,0,sizeof(indegree));
        memset(L,0,sizeof(L));
        for(i=0; i<4; i++)
        {
            for(j=0; j<4; j++)
            {
                char x;
                scanf("%c",&x);
                string::iterator y;
                for (y=cover[i][j].begin(); y!=cover[i][j].end(); ++y)
                {
                    if((*y)!=x&&L[x-'0'][(*y)-'0']==0)
                    {
                        L[x-'0'][(*y)-'0']=1;
                        indegree[(*y)-'0']++;
                    }
                }
                getchar();
            }
        }
        cin>>s;
        getchar();
        /**
        for(i=1; i<10; i++)
        {
            cout<<i<<":";
            for(j=0; j<10; j++)
            {
                if(L[i][j]==1)
                    cout<<j<<" ";
            }
            cout<<endl;
        }
        cout<<"indegree:";
        for(i=1; i<10; i++) cout<<indegree[i]<<" ";
        cout<<endl;
        */
        int flag=TopSort();
        if(flag) cout<<"THESE WINDOWS ARE CLEAN"<<endl;
        else cout<<"THESE WINDOWS ARE BROKEN"<<endl;
    }
    return 0;
}
int TopSort()
{
    int i,j;
    int n=9;
    int sign=0;
    while(n--)
    {
        sign=0;
        for(i=1; i<10; i++)
        {
            if(indegree[i]==0) sign=i;
        }
        if(sign>0)
        {
            for(j=0; j<10; j++)
            {
                if(L[sign][j])
                    indegree[j]--;
            }
            indegree[sign]=-1;
        }
        else if(sign==0) return 0;
    }
    return 1;
}