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
5
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:
3 4
Solution： 使用邻接矩阵来保存这个有向矩阵，并且把每个节点的入度计算，遍历判断的序列，每经过一个节点就判断该节点入度是不是为0，若不是，说明不是拓扑序列每经过一个节点，将其指向节点的入度-1，表明指向节点的父节点遍历完毕，从而保证了整个序列是个拓扑序列 1 #include <iostream>
2 #include <vector>
3 #include <queue>
4 #include <algorithm>
5 using namespace std;
6
7
8 int main()
9 {
10 int n, m, k;
11 cin >> n >> m;
12 vector<vector<int>>v(n + 1);
13 vector<int>in(n + 1, 0), temp, res;//节点的入度
14 for (int i = 0; i < m; ++i)
15 {
16 int a, b;
17 cin >> a >> b;
18 v[a].push_back(b);
19 in[b]++;
20 }
21 cin >> k;
22 for (int i = 0; i < k; ++i)
23 {
24 bool flag = true;
25 temp = in;
26 for (int j = 0; j < n; ++j)
27 {
28 int x;
29 cin >> x;
30 if (temp[x] != 0)flag = false;
31 for (auto a : v[x])--temp[a];//出现一次入度减一
32 }
33 if (!flag)
34 res.push_back(i);
35 }
36 for (int i = 0; i < res.size(); ++i)
37 cout << (i == 0 ? "" : " ") << res[i];
38 return 0;
39 }
原文地址：https://www.cnblogs.com/zzw1024/p/11909324.html