Question:
In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 4
node 0 should be visited before node 1
node 2 should be visited before node 1
node 3 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 and node 3, node 0 and node 3 can be visited first.
Since visiting node 4 requires visiting node 0 first, after node 0 is visited, node 4 can be visited.
Since visiting node 2 requires visiting node 3 first, after node 3 is visited, node 2 can be visited.
Since visiting node 1 requires visiting node 0, node 2 first, after node 0 and node 2 are visited, node 1 can be visited. So the solution is: 0,3,4,2,1.

In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 1
node 1 should be visited before node 2
node 3 should be visited before node 1
node 3 should be visited before node 2
node 4 should be visited before node 3
node 4 should be visited before node 0
node 4 should be visited before node 1
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 4, node 4 can be visited first.
Since visiting node 0, node 3 requires visiting node 4 first, after node 4 is visited, node 0 and node 3 can be visited.
Since visiting node 1 requires visiting node 0, node 3, node 4 first, after node 0, node 3, and node 4 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3 first, after node 1 and node 3 are visited, node 2 can be visited. So the solution is: 4,0,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 3
node 1 should be visited before node 2
node 3 should be visited before node 2
node 4 should be visited before node 1
node 4 should be visited before node 2
node 5 should be visited before node 1
node 5 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 node 4 and node 5, node 0 node 4 and node 5 can be visited first.
Since visiting node 3 requires visiting node 0 first, after node 0 is visited, node 3 can be visited.
Since visiting node 1 requires visiting node 4, node 5 first, after node 4 and node 5 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3, node 4, node 5 first, after node 1, node 3, node 4, and node 5 are visited, node 2 can be visited. So the solution is: 0,4,5,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 5
node 1 should be visited before node 2
node 1 should be visited before node 0
node 3 should be visited before node 0
node 3 should be visited before node 5
node 4 should be visited before node 3
node 4 should be visited before node 2
node 4 should be visited before node 0
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 1 and node 4, node 1 and node 4 can be visited first.
Since visiting node 2 requires visiting node 1, node 4 first, after node 1 and node 4 are visited, node 2 can be visited.
Since visiting node 3 requires visiting node 4 first, after node 4 is visited, node 3 can be visited.
Since visiting node 0 requires visiting node 1, node 3, node 4 first, after node 1, node 3, and node 4 are visited, node 0 can be visited.
Since visiting node 5 requires visiting node 0, node 3 first, after node 0 and node 3 are visited, node 5 can be visited. So the solution is: 1,4,2,3,0,5.

In a directed graph with 7 nodes numbered from 0 to 6:
node 0 should be visited before node 6
node 2 should be visited before node 0
node 2 should be visited before node 5
node 4 should be visited before node 1
node 4 should be visited before node 3
node 6 should be visited before node 3
node 6 should be visited before node 5
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 2 and node 4, node 2 and node 4 can be visited first.
Since visiting node 0 requires visiting node 2 first, after node 2 is visited, node 0 can be visited.
Since visiting node 1 requires visiting node 4 first, after node 4 is visited, node 1 can be visited.
Since visiting node 6 requires visiting node 0 first, after node 0 is visited, node 6 can be visited.
Since visiting node 5 requires visiting node 2, node 6 first, after node 2 and node 6 are visited, node 5 can be visited.
Since visiting node 3 requires visiting node 4, node 6 first, after node 4 and node 6 are visited, node 3 can be visited. So the solution is: 2,4,0,1,6,5,3.

In a directed graph with 14 nodes numbered from 0 to 13:
node 0 should be visited before node 7
node 0 should be visited before node 3
node 0 should be visited before node 13
node 0 should be visited before node 9
node 0 should be visited before node 11
node 1 should be visited before node 5
node 1 should be visited before node 8
node 1 should be visited before node 7
node 1 should be visited before node 3
node 1 should be visited before node 13
node 1 should be visited before node 12
node 1 should be visited before node 9
node 1 should be visited before node 11
node 2 should be visited before node 6
node 2 should be visited before node 0
node 2 should be visited before node 3
node 2 should be visited before node 11
node 3 should be visited before node 13
node 3 should be visited before node 12
node 3 should be visited before node 9
node 3 should be visited before node 4
node 4 should be visited before node 11
node 5 should be visited before node 10
node 5 should be visited before node 0
node 5 should be visited before node 7
node 5 should be visited before node 3
node 5 should be visited before node 13
node 5 should be visited before node 12
node 5 should be visited before node 9
node 5 should be visited before node 4
node 5 should be visited before node 11
node 6 should be visited before node 0
node 6 should be visited before node 7
node 6 should be visited before node 3
node 6 should be visited before node 13
node 6 should be visited before node 4
node 6 should be visited before node 11
node 7 should be visited before node 13
node 7 should be visited before node 9
node 7 should be visited before node 4
node 7 should be visited before node 11
node 8 should be visited before node 6
node 8 should be visited before node 7
node 8 should be visited before node 3
node 8 should be visited before node 13
node 8 should be visited before node 9
node 8 should be visited before node 11
node 9 should be visited before node 11
node 10 should be visited before node 8
node 10 should be visited before node 6
node 10 should be visited before node 0
node 10 should be visited before node 7
node 10 should be visited before node 13
node 10 should be visited before node 12
node 10 should be visited before node 11
node 12 should be visited before node 4
node 13 should be visited before node 9
node 13 should be visited before node 11
Q: Can all the nodes be visited? Give the solution.
A:

Answer: The solution is: 1,2,5,10,8,6,0,7,3,13,12,9,4,11.


Question:
In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 4
node 0 should be visited before node 1
node 2 should be visited before node 1
node 3 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 and node 3, node 0 and node 3 can be visited first.
Since visiting node 4 requires visiting node 0 first, after node 0 is visited, node 4 can be visited.
Since visiting node 2 requires visiting node 3 first, after node 3 is visited, node 2 can be visited.
Since visiting node 1 requires visiting node 0, node 2 first, after node 0 and node 2 are visited, node 1 can be visited. So the solution is: 0,3,4,2,1.

In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 1
node 1 should be visited before node 2
node 3 should be visited before node 1
node 3 should be visited before node 2
node 4 should be visited before node 3
node 4 should be visited before node 0
node 4 should be visited before node 1
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 4, node 4 can be visited first.
Since visiting node 0, node 3 requires visiting node 4 first, after node 4 is visited, node 0 and node 3 can be visited.
Since visiting node 1 requires visiting node 0, node 3, node 4 first, after node 0, node 3, and node 4 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3 first, after node 1 and node 3 are visited, node 2 can be visited. So the solution is: 4,0,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 3
node 1 should be visited before node 2
node 3 should be visited before node 2
node 4 should be visited before node 1
node 4 should be visited before node 2
node 5 should be visited before node 1
node 5 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 node 4 and node 5, node 0 node 4 and node 5 can be visited first.
Since visiting node 3 requires visiting node 0 first, after node 0 is visited, node 3 can be visited.
Since visiting node 1 requires visiting node 4, node 5 first, after node 4 and node 5 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3, node 4, node 5 first, after node 1, node 3, node 4, and node 5 are visited, node 2 can be visited. So the solution is: 0,4,5,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 5
node 1 should be visited before node 2
node 1 should be visited before node 0
node 3 should be visited before node 0
node 3 should be visited before node 5
node 4 should be visited before node 3
node 4 should be visited before node 2
node 4 should be visited before node 0
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 1 and node 4, node 1 and node 4 can be visited first.
Since visiting node 2 requires visiting node 1, node 4 first, after node 1 and node 4 are visited, node 2 can be visited.
Since visiting node 3 requires visiting node 4 first, after node 4 is visited, node 3 can be visited.
Since visiting node 0 requires visiting node 1, node 3, node 4 first, after node 1, node 3, and node 4 are visited, node 0 can be visited.
Since visiting node 5 requires visiting node 0, node 3 first, after node 0 and node 3 are visited, node 5 can be visited. So the solution is: 1,4,2,3,0,5.

In a directed graph with 7 nodes numbered from 0 to 6:
node 0 should be visited before node 6
node 2 should be visited before node 0
node 2 should be visited before node 5
node 4 should be visited before node 1
node 4 should be visited before node 3
node 6 should be visited before node 3
node 6 should be visited before node 5
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 2 and node 4, node 2 and node 4 can be visited first.
Since visiting node 0 requires visiting node 2 first, after node 2 is visited, node 0 can be visited.
Since visiting node 1 requires visiting node 4 first, after node 4 is visited, node 1 can be visited.
Since visiting node 6 requires visiting node 0 first, after node 0 is visited, node 6 can be visited.
Since visiting node 5 requires visiting node 2, node 6 first, after node 2 and node 6 are visited, node 5 can be visited.
Since visiting node 3 requires visiting node 4, node 6 first, after node 4 and node 6 are visited, node 3 can be visited. So the solution is: 2,4,0,1,6,5,3.

In a directed graph with 12 nodes numbered from 0 to 11:
node 0 should be visited before node 4
node 0 should be visited before node 8
node 0 should be visited before node 10
node 0 should be visited before node 7
node 1 should be visited before node 9
node 2 should be visited before node 3
node 4 should be visited before node 11
node 5 should be visited before node 1
node 5 should be visited before node 2
node 5 should be visited before node 4
node 5 should be visited before node 3
node 5 should be visited before node 11
node 5 should be visited before node 7
node 6 should be visited before node 0
node 6 should be visited before node 4
node 6 should be visited before node 8
node 6 should be visited before node 7
node 8 should be visited before node 7
node 10 should be visited before node 7
node 10 should be visited before node 9
node 11 should be visited before node 7
node 11 should be visited before node 9
Q: Can all the nodes be visited? Give the solution.
A:

Answer: The solution is: 5,6,1,2,0,3,4,8,10,11,7,9.


Question:
In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 4
node 0 should be visited before node 1
node 2 should be visited before node 1
node 3 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 and node 3, node 0 and node 3 can be visited first.
Since visiting node 4 requires visiting node 0 first, after node 0 is visited, node 4 can be visited.
Since visiting node 2 requires visiting node 3 first, after node 3 is visited, node 2 can be visited.
Since visiting node 1 requires visiting node 0, node 2 first, after node 0 and node 2 are visited, node 1 can be visited. So the solution is: 0,3,4,2,1.

In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 1
node 1 should be visited before node 2
node 3 should be visited before node 1
node 3 should be visited before node 2
node 4 should be visited before node 3
node 4 should be visited before node 0
node 4 should be visited before node 1
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 4, node 4 can be visited first.
Since visiting node 0, node 3 requires visiting node 4 first, after node 4 is visited, node 0 and node 3 can be visited.
Since visiting node 1 requires visiting node 0, node 3, node 4 first, after node 0, node 3, and node 4 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3 first, after node 1 and node 3 are visited, node 2 can be visited. So the solution is: 4,0,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 3
node 1 should be visited before node 2
node 3 should be visited before node 2
node 4 should be visited before node 1
node 4 should be visited before node 2
node 5 should be visited before node 1
node 5 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 node 4 and node 5, node 0 node 4 and node 5 can be visited first.
Since visiting node 3 requires visiting node 0 first, after node 0 is visited, node 3 can be visited.
Since visiting node 1 requires visiting node 4, node 5 first, after node 4 and node 5 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3, node 4, node 5 first, after node 1, node 3, node 4, and node 5 are visited, node 2 can be visited. So the solution is: 0,4,5,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 5
node 1 should be visited before node 2
node 1 should be visited before node 0
node 3 should be visited before node 0
node 3 should be visited before node 5
node 4 should be visited before node 3
node 4 should be visited before node 2
node 4 should be visited before node 0
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 1 and node 4, node 1 and node 4 can be visited first.
Since visiting node 2 requires visiting node 1, node 4 first, after node 1 and node 4 are visited, node 2 can be visited.
Since visiting node 3 requires visiting node 4 first, after node 4 is visited, node 3 can be visited.
Since visiting node 0 requires visiting node 1, node 3, node 4 first, after node 1, node 3, and node 4 are visited, node 0 can be visited.
Since visiting node 5 requires visiting node 0, node 3 first, after node 0 and node 3 are visited, node 5 can be visited. So the solution is: 1,4,2,3,0,5.

In a directed graph with 7 nodes numbered from 0 to 6:
node 0 should be visited before node 6
node 2 should be visited before node 0
node 2 should be visited before node 5
node 4 should be visited before node 1
node 4 should be visited before node 3
node 6 should be visited before node 3
node 6 should be visited before node 5
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 2 and node 4, node 2 and node 4 can be visited first.
Since visiting node 0 requires visiting node 2 first, after node 2 is visited, node 0 can be visited.
Since visiting node 1 requires visiting node 4 first, after node 4 is visited, node 1 can be visited.
Since visiting node 6 requires visiting node 0 first, after node 0 is visited, node 6 can be visited.
Since visiting node 5 requires visiting node 2, node 6 first, after node 2 and node 6 are visited, node 5 can be visited.
Since visiting node 3 requires visiting node 4, node 6 first, after node 4 and node 6 are visited, node 3 can be visited. So the solution is: 2,4,0,1,6,5,3.

In a directed graph with 7 nodes numbered from 0 to 6:
node 0 should be visited before node 6
node 2 should be visited before node 0
node 2 should be visited before node 5
node 4 should be visited before node 1
node 4 should be visited before node 3
node 6 should be visited before node 3
node 6 should be visited before node 5
Q: Can all the nodes be visited? Give the solution.
A:

Answer: The solution is: 2,4,0,1,6,3,5.


Question:
In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 4
node 0 should be visited before node 1
node 2 should be visited before node 1
node 3 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 and node 3, node 0 and node 3 can be visited first.
Since visiting node 4 requires visiting node 0 first, after node 0 is visited, node 4 can be visited.
Since visiting node 2 requires visiting node 3 first, after node 3 is visited, node 2 can be visited.
Since visiting node 1 requires visiting node 0, node 2 first, after node 0 and node 2 are visited, node 1 can be visited. So the solution is: 0,3,4,2,1.

In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 1
node 1 should be visited before node 2
node 3 should be visited before node 1
node 3 should be visited before node 2
node 4 should be visited before node 3
node 4 should be visited before node 0
node 4 should be visited before node 1
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 4, node 4 can be visited first.
Since visiting node 0, node 3 requires visiting node 4 first, after node 4 is visited, node 0 and node 3 can be visited.
Since visiting node 1 requires visiting node 0, node 3, node 4 first, after node 0, node 3, and node 4 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3 first, after node 1 and node 3 are visited, node 2 can be visited. So the solution is: 4,0,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 3
node 1 should be visited before node 2
node 3 should be visited before node 2
node 4 should be visited before node 1
node 4 should be visited before node 2
node 5 should be visited before node 1
node 5 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 node 4 and node 5, node 0 node 4 and node 5 can be visited first.
Since visiting node 3 requires visiting node 0 first, after node 0 is visited, node 3 can be visited.
Since visiting node 1 requires visiting node 4, node 5 first, after node 4 and node 5 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3, node 4, node 5 first, after node 1, node 3, node 4, and node 5 are visited, node 2 can be visited. So the solution is: 0,4,5,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 5
node 1 should be visited before node 2
node 1 should be visited before node 0
node 3 should be visited before node 0
node 3 should be visited before node 5
node 4 should be visited before node 3
node 4 should be visited before node 2
node 4 should be visited before node 0
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 1 and node 4, node 1 and node 4 can be visited first.
Since visiting node 2 requires visiting node 1, node 4 first, after node 1 and node 4 are visited, node 2 can be visited.
Since visiting node 3 requires visiting node 4 first, after node 4 is visited, node 3 can be visited.
Since visiting node 0 requires visiting node 1, node 3, node 4 first, after node 1, node 3, and node 4 are visited, node 0 can be visited.
Since visiting node 5 requires visiting node 0, node 3 first, after node 0 and node 3 are visited, node 5 can be visited. So the solution is: 1,4,2,3,0,5.

In a directed graph with 7 nodes numbered from 0 to 6:
node 0 should be visited before node 6
node 2 should be visited before node 0
node 2 should be visited before node 5
node 4 should be visited before node 1
node 4 should be visited before node 3
node 6 should be visited before node 3
node 6 should be visited before node 5
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 2 and node 4, node 2 and node 4 can be visited first.
Since visiting node 0 requires visiting node 2 first, after node 2 is visited, node 0 can be visited.
Since visiting node 1 requires visiting node 4 first, after node 4 is visited, node 1 can be visited.
Since visiting node 6 requires visiting node 0 first, after node 0 is visited, node 6 can be visited.
Since visiting node 5 requires visiting node 2, node 6 first, after node 2 and node 6 are visited, node 5 can be visited.
Since visiting node 3 requires visiting node 4, node 6 first, after node 4 and node 6 are visited, node 3 can be visited. So the solution is: 2,4,0,1,6,5,3.

In a directed graph with 22 nodes numbered from 0 to 21:
node 1 should be visited before node 16
node 1 should be visited before node 4
node 1 should be visited before node 12
node 2 should be visited before node 9
node 3 should be visited before node 4
node 3 should be visited before node 11
node 3 should be visited before node 0
node 3 should be visited before node 9
node 3 should be visited before node 15
node 4 should be visited before node 7
node 4 should be visited before node 0
node 4 should be visited before node 9
node 4 should be visited before node 15
node 5 should be visited before node 20
node 5 should be visited before node 9
node 6 should be visited before node 17
node 6 should be visited before node 1
node 6 should be visited before node 3
node 6 should be visited before node 13
node 6 should be visited before node 4
node 6 should be visited before node 12
node 6 should be visited before node 7
node 6 should be visited before node 11
node 6 should be visited before node 20
node 6 should be visited before node 0
node 6 should be visited before node 9
node 7 should be visited before node 2
node 8 should be visited before node 14
node 8 should be visited before node 1
node 8 should be visited before node 16
node 8 should be visited before node 5
node 8 should be visited before node 13
node 8 should be visited before node 12
node 8 should be visited before node 7
node 8 should be visited before node 15
node 8 should be visited before node 10
node 9 should be visited before node 15
node 11 should be visited before node 10
node 12 should be visited before node 19
node 12 should be visited before node 7
node 12 should be visited before node 20
node 12 should be visited before node 2
node 14 should be visited before node 6
node 14 should be visited before node 3
node 14 should be visited before node 16
node 14 should be visited before node 5
node 14 should be visited before node 13
node 14 should be visited before node 12
node 14 should be visited before node 7
node 14 should be visited before node 9
node 14 should be visited before node 15
node 15 should be visited before node 10
node 16 should be visited before node 13
node 16 should be visited before node 12
node 16 should be visited before node 19
node 16 should be visited before node 7
node 16 should be visited before node 11
node 16 should be visited before node 0
node 16 should be visited before node 2
node 17 should be visited before node 1
node 17 should be visited before node 5
node 17 should be visited before node 18
node 17 should be visited before node 13
node 17 should be visited before node 11
node 17 should be visited before node 2
node 17 should be visited before node 9
node 17 should be visited before node 15
node 18 should be visited before node 13
node 18 should be visited before node 4
node 18 should be visited before node 20
node 18 should be visited before node 0
node 18 should be visited before node 9
node 18 should be visited before node 10
node 19 should be visited before node 20
node 19 should be visited before node 10
node 20 should be visited before node 15
node 21 should be visited before node 1
node 21 should be visited before node 3
node 21 should be visited before node 5
node 21 should be visited before node 18
node 21 should be visited before node 4
node 21 should be visited before node 19
node 21 should be visited before node 7
node 21 should be visited before node 0
node 21 should be visited before node 2
node 21 should be visited before node 15
node 21 should be visited before node 10
Q: Can all the nodes be visited? Give the solution.
A:

Answer: The solution is: 8,21,14,6,17,3,1,5,18,16,4,13,12,11,0,19,7,20,2,9,15,10.


Question:
In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 4
node 0 should be visited before node 1
node 2 should be visited before node 1
node 3 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 and node 3, node 0 and node 3 can be visited first.
Since visiting node 4 requires visiting node 0 first, after node 0 is visited, node 4 can be visited.
Since visiting node 2 requires visiting node 3 first, after node 3 is visited, node 2 can be visited.
Since visiting node 1 requires visiting node 0, node 2 first, after node 0 and node 2 are visited, node 1 can be visited. So the solution is: 0,3,4,2,1.

In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 1
node 1 should be visited before node 2
node 3 should be visited before node 1
node 3 should be visited before node 2
node 4 should be visited before node 3
node 4 should be visited before node 0
node 4 should be visited before node 1
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 4, node 4 can be visited first.
Since visiting node 0, node 3 requires visiting node 4 first, after node 4 is visited, node 0 and node 3 can be visited.
Since visiting node 1 requires visiting node 0, node 3, node 4 first, after node 0, node 3, and node 4 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3 first, after node 1 and node 3 are visited, node 2 can be visited. So the solution is: 4,0,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 3
node 1 should be visited before node 2
node 3 should be visited before node 2
node 4 should be visited before node 1
node 4 should be visited before node 2
node 5 should be visited before node 1
node 5 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 node 4 and node 5, node 0 node 4 and node 5 can be visited first.
Since visiting node 3 requires visiting node 0 first, after node 0 is visited, node 3 can be visited.
Since visiting node 1 requires visiting node 4, node 5 first, after node 4 and node 5 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3, node 4, node 5 first, after node 1, node 3, node 4, and node 5 are visited, node 2 can be visited. So the solution is: 0,4,5,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 5
node 1 should be visited before node 2
node 1 should be visited before node 0
node 3 should be visited before node 0
node 3 should be visited before node 5
node 4 should be visited before node 3
node 4 should be visited before node 2
node 4 should be visited before node 0
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 1 and node 4, node 1 and node 4 can be visited first.
Since visiting node 2 requires visiting node 1, node 4 first, after node 1 and node 4 are visited, node 2 can be visited.
Since visiting node 3 requires visiting node 4 first, after node 4 is visited, node 3 can be visited.
Since visiting node 0 requires visiting node 1, node 3, node 4 first, after node 1, node 3, and node 4 are visited, node 0 can be visited.
Since visiting node 5 requires visiting node 0, node 3 first, after node 0 and node 3 are visited, node 5 can be visited. So the solution is: 1,4,2,3,0,5.

In a directed graph with 7 nodes numbered from 0 to 6:
node 0 should be visited before node 6
node 2 should be visited before node 0
node 2 should be visited before node 5
node 4 should be visited before node 1
node 4 should be visited before node 3
node 6 should be visited before node 3
node 6 should be visited before node 5
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 2 and node 4, node 2 and node 4 can be visited first.
Since visiting node 0 requires visiting node 2 first, after node 2 is visited, node 0 can be visited.
Since visiting node 1 requires visiting node 4 first, after node 4 is visited, node 1 can be visited.
Since visiting node 6 requires visiting node 0 first, after node 0 is visited, node 6 can be visited.
Since visiting node 5 requires visiting node 2, node 6 first, after node 2 and node 6 are visited, node 5 can be visited.
Since visiting node 3 requires visiting node 4, node 6 first, after node 4 and node 6 are visited, node 3 can be visited. So the solution is: 2,4,0,1,6,5,3.

In a directed graph with 24 nodes numbered from 0 to 23:
node 0 should be visited before node 5
node 0 should be visited before node 8
node 0 should be visited before node 18
node 0 should be visited before node 14
node 0 should be visited before node 16
node 0 should be visited before node 11
node 1 should be visited before node 21
node 1 should be visited before node 18
node 1 should be visited before node 11
node 2 should be visited before node 22
node 2 should be visited before node 13
node 2 should be visited before node 15
node 2 should be visited before node 7
node 2 should be visited before node 16
node 2 should be visited before node 11
node 2 should be visited before node 12
node 2 should be visited before node 20
node 3 should be visited before node 15
node 3 should be visited before node 0
node 3 should be visited before node 6
node 3 should be visited before node 1
node 3 should be visited before node 18
node 3 should be visited before node 14
node 3 should be visited before node 11
node 3 should be visited before node 17
node 4 should be visited before node 15
node 4 should be visited before node 0
node 4 should be visited before node 6
node 4 should be visited before node 8
node 4 should be visited before node 1
node 4 should be visited before node 9
node 4 should be visited before node 18
node 4 should be visited before node 16
node 4 should be visited before node 11
node 4 should be visited before node 17
node 5 should be visited before node 6
node 5 should be visited before node 1
node 6 should be visited before node 17
node 6 should be visited before node 20
node 7 should be visited before node 9
node 8 should be visited before node 17
node 8 should be visited before node 20
node 9 should be visited before node 12
node 10 should be visited before node 15
node 10 should be visited before node 1
node 10 should be visited before node 18
node 11 should be visited before node 17
node 13 should be visited before node 8
node 13 should be visited before node 9
node 13 should be visited before node 11
node 13 should be visited before node 12
node 14 should be visited before node 16
node 15 should be visited before node 0
node 15 should be visited before node 6
node 15 should be visited before node 8
node 15 should be visited before node 1
node 15 should be visited before node 14
node 15 should be visited before node 16
node 15 should be visited before node 11
node 16 should be visited before node 11
node 16 should be visited before node 17
node 18 should be visited before node 16
node 18 should be visited before node 12
node 18 should be visited before node 17
node 18 should be visited before node 20
node 19 should be visited before node 15
node 19 should be visited before node 9
node 19 should be visited before node 21
node 19 should be visited before node 14
node 19 should be visited before node 17
node 19 should be visited before node 20
node 21 should be visited before node 18
node 21 should be visited before node 11
node 21 should be visited before node 20
node 22 should be visited before node 15
node 22 should be visited before node 7
node 22 should be visited before node 18
node 22 should be visited before node 14
node 22 should be visited before node 17
node 23 should be visited before node 13
node 23 should be visited before node 6
node 23 should be visited before node 21
node 23 should be visited before node 16
node 23 should be visited before node 20
Q: Can all the nodes be visited? Give the solution.
A:

Answer: The solution is: 2,3,4,10,19,23,22,13,15,7,0,9,5,8,14,6,1,21,18,16,12,20,11,17.


Question:
In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 4
node 0 should be visited before node 1
node 2 should be visited before node 1
node 3 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 and node 3, node 0 and node 3 can be visited first.
Since visiting node 4 requires visiting node 0 first, after node 0 is visited, node 4 can be visited.
Since visiting node 2 requires visiting node 3 first, after node 3 is visited, node 2 can be visited.
Since visiting node 1 requires visiting node 0, node 2 first, after node 0 and node 2 are visited, node 1 can be visited. So the solution is: 0,3,4,2,1.

In a directed graph with 5 nodes numbered from 0 to 4:
node 0 should be visited before node 1
node 1 should be visited before node 2
node 3 should be visited before node 1
node 3 should be visited before node 2
node 4 should be visited before node 3
node 4 should be visited before node 0
node 4 should be visited before node 1
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 4, node 4 can be visited first.
Since visiting node 0, node 3 requires visiting node 4 first, after node 4 is visited, node 0 and node 3 can be visited.
Since visiting node 1 requires visiting node 0, node 3, node 4 first, after node 0, node 3, and node 4 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3 first, after node 1 and node 3 are visited, node 2 can be visited. So the solution is: 4,0,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 3
node 1 should be visited before node 2
node 3 should be visited before node 2
node 4 should be visited before node 1
node 4 should be visited before node 2
node 5 should be visited before node 1
node 5 should be visited before node 2
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 0 node 4 and node 5, node 0 node 4 and node 5 can be visited first.
Since visiting node 3 requires visiting node 0 first, after node 0 is visited, node 3 can be visited.
Since visiting node 1 requires visiting node 4, node 5 first, after node 4 and node 5 are visited, node 1 can be visited.
Since visiting node 2 requires visiting node 1, node 3, node 4, node 5 first, after node 1, node 3, node 4, and node 5 are visited, node 2 can be visited. So the solution is: 0,4,5,3,1,2.

In a directed graph with 6 nodes numbered from 0 to 5:
node 0 should be visited before node 5
node 1 should be visited before node 2
node 1 should be visited before node 0
node 3 should be visited before node 0
node 3 should be visited before node 5
node 4 should be visited before node 3
node 4 should be visited before node 2
node 4 should be visited before node 0
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 1 and node 4, node 1 and node 4 can be visited first.
Since visiting node 2 requires visiting node 1, node 4 first, after node 1 and node 4 are visited, node 2 can be visited.
Since visiting node 3 requires visiting node 4 first, after node 4 is visited, node 3 can be visited.
Since visiting node 0 requires visiting node 1, node 3, node 4 first, after node 1, node 3, and node 4 are visited, node 0 can be visited.
Since visiting node 5 requires visiting node 0, node 3 first, after node 0 and node 3 are visited, node 5 can be visited. So the solution is: 1,4,2,3,0,5.

In a directed graph with 7 nodes numbered from 0 to 6:
node 0 should be visited before node 6
node 2 should be visited before node 0
node 2 should be visited before node 5
node 4 should be visited before node 1
node 4 should be visited before node 3
node 6 should be visited before node 3
node 6 should be visited before node 5
Q: Can all the nodes be visited? Give the solution.
A: Since no nodes are required to be visited before node 2 and node 4, node 2 and node 4 can be visited first.
Since visiting node 0 requires visiting node 2 first, after node 2 is visited, node 0 can be visited.
Since visiting node 1 requires visiting node 4 first, after node 4 is visited, node 1 can be visited.
Since visiting node 6 requires visiting node 0 first, after node 0 is visited, node 6 can be visited.
Since visiting node 5 requires visiting node 2, node 6 first, after node 2 and node 6 are visited, node 5 can be visited.
Since visiting node 3 requires visiting node 4, node 6 first, after node 4 and node 6 are visited, node 3 can be visited. So the solution is: 2,4,0,1,6,5,3.

In a directed graph with 19 nodes numbered from 0 to 18:
node 0 should be visited before node 4
node 0 should be visited before node 17
node 0 should be visited before node 16
node 2 should be visited before node 6
node 2 should be visited before node 18
node 2 should be visited before node 11
node 2 should be visited before node 17
node 2 should be visited before node 1
node 2 should be visited before node 3
node 3 should be visited before node 16
node 4 should be visited before node 18
node 4 should be visited before node 11
node 4 should be visited before node 17
node 4 should be visited before node 1
node 4 should be visited before node 3
node 4 should be visited before node 16
node 5 should be visited before node 15
node 5 should be visited before node 11
node 5 should be visited before node 17
node 5 should be visited before node 1
node 5 should be visited before node 3
node 6 should be visited before node 12
node 6 should be visited before node 15
node 6 should be visited before node 0
node 6 should be visited before node 11
node 6 should be visited before node 3
node 6 should be visited before node 16
node 7 should be visited before node 15
node 7 should be visited before node 18
node 7 should be visited before node 16
node 8 should be visited before node 2
node 8 should be visited before node 10
node 8 should be visited before node 5
node 8 should be visited before node 0
node 8 should be visited before node 4
node 8 should be visited before node 18
node 8 should be visited before node 17
node 8 should be visited before node 16
node 9 should be visited before node 14
node 9 should be visited before node 8
node 9 should be visited before node 12
node 9 should be visited before node 15
node 9 should be visited before node 0
node 9 should be visited before node 4
node 9 should be visited before node 18
node 9 should be visited before node 11
node 9 should be visited before node 1
node 9 should be visited before node 3
node 10 should be visited before node 5
node 10 should be visited before node 15
node 10 should be visited before node 4
node 10 should be visited before node 11
node 10 should be visited before node 3
node 11 should be visited before node 16
node 12 should be visited before node 0
node 12 should be visited before node 1
node 13 should be visited before node 2
node 13 should be visited before node 6
node 13 should be visited before node 12
node 13 should be visited before node 4
node 13 should be visited before node 11
node 13 should be visited before node 17
node 13 should be visited before node 3
node 14 should be visited before node 7
node 14 should be visited before node 10
node 14 should be visited before node 5
node 14 should be visited before node 3
node 14 should be visited before node 16
node 15 should be visited before node 0
node 15 should be visited before node 4
node 15 should be visited before node 18
node 15 should be visited before node 1
node 15 should be visited before node 3
node 15 should be visited before node 16
node 17 should be visited before node 1
node 18 should be visited before node 17
node 18 should be visited before node 1
node 18 should be visited before node 3
node 18 should be visited before node 16
Q: Can all the nodes be visited? Give the solution.
A:

Answer: The solution is: 9,13,14,8,7,2,10,6,5,12,15,0,4,18,11,17,3,1,16.