public void OneEdgeTest()
{
var edges = new List <DirectedEdge <int> >()
{
new DirectedEdge <int>(new GraphNode <int>(1), new GraphNode <int>(2))
};
var graph = new DirectedGraph <int>(edges);
var topOrder = new TopologicalOrdering <int>(graph);
Assert.Equal(new [] { 2, 1 }, topOrder.GetTopologicalOrdering());
}
public void NoOrderTest()
{
var node0 = new GraphNode <int>(0);
var node1 = new GraphNode <int>(1);
var edges = new List <DirectedEdge <int> >()
{
new DirectedEdge <int>(node1, node0),
new DirectedEdge <int>(node0, node1),
};
var graph = new DirectedGraph <int>(edges);
var topOrder = new TopologicalOrdering <int>(graph);
Assert.Equal(new int[] { }, topOrder.GetTopologicalOrdering());
}
public void FourEdgeTest()
{
var node0 = new GraphNode <int>(0);
var node1 = new GraphNode <int>(1);
var node2 = new GraphNode <int>(2);
var node3 = new GraphNode <int>(3);
var edges = new List <DirectedEdge <int> >()
{
new DirectedEdge <int>(node1, node0),
new DirectedEdge <int>(node2, node0),
new DirectedEdge <int>(node3, node1),
new DirectedEdge <int>(node3, node2),
};
var graph = new DirectedGraph <int>(edges);
var topOrder = new TopologicalOrdering <int>(graph);
Assert.Equal(new[] { 0, 1, 2, 3 }, topOrder.GetTopologicalOrdering());
}
//https://leetcode.com/problems/course-schedule-ii/
public int[] FindOrder(int numCourses, int[][] prerequisites)
{
var nodes = new List <GraphNode <int> >(numCourses);
for (var i = 0; i < numCourses; i++)
{
nodes.Add(new GraphNode <int>(i));
}
var edges = new List <DirectedEdge <int> >(prerequisites.GetLength(0));
for (var i = 0; i < prerequisites.GetLength(0); i++)
{
edges.Add(new DirectedEdge <int>(nodes[prerequisites[i][0]], nodes[prerequisites[i][1]]));
}
var diGraph = new DirectedGraph <int>(nodes, edges);
var topSorter = new TopologicalOrdering <int>(diGraph);
return(topSorter.GetTopologicalOrdering()?.ToArray());
}
