A1146 Topological Order（25分）PAT 甲级(Advanced Level) Practice（C++）满分题解【拓扑排序】

This is a problem given in the Graduate Entrance Exam in 2018: Which of the following is NOT a topological order obtained from the given directed graph? Now you are supposed to write a program to test each of the options.

Input Specification:

Each input file contains one test case. For each case, the first line gives two positive integers N (≤ 1,000), the number of vertices in the graph, and M (≤ 10,000), the number of directed edges. Then M lines follow, each gives the start and the end vertices of an edge. The vertices are numbered from 1 to N. After the graph, there is another positive integer K (≤ 100). Then K lines of query follow, each gives a permutation of all the vertices. All the numbers in a line are separated by a space.

Output Specification:

Print in a line all the indices of queries which correspond to "NOT a topological order". The indices start from zero. All the numbers are separated by a space, and there must no extra space at the beginning or the end of the line. It is graranteed that there is at least one answer.

Sample Input:

6 8
1 2
1 3
5 2
5 4
2 3
2 6
3 4
6 4
6
5 2 3 6 4 1
1 5 2 3 6 4
5 1 2 6 3 4
5 1 2 3 6 4
5 2 1 6 3 4
1 2 3 4 5 6

Sample Output:

0 4 5

 

代码如下：

#include
using namespace std;
int main()
{
    int n,m,k,v1,v2,a,flag=0,in[1010];
    cin>>n>>m;
    vector v[1010];
    for(int i=1;i<=m;i++)
    {
        cin>>v1>>v2;
        v[v1].push_back(v2);
        in[v2]++;//入度
    }
    cin>>k;
    for(int i=0;i tin(in,in+n+1);
        for(int j=0;j>a;
            if(tin[a]!=0)judge=0;//入度不为0，不是拓扑序列，还不能输出
            for(int it:v[a])tin[it]--;//每次选中某个点后要将它所指向的所有结点的入度-1
        }
        if(judge==1)continue;
        printf("%s%d",flag==1?" ":"",i);
        flag=1;
    }
    cout<

运行结果如下：

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