private bool orderCourses(CourseGraph graph, int numCourse, int[][] prerequisites)
{
int numDependencies = prerequisites.Count();
List <CourseGraphNode> nodes = graph.nodes;
CourseGraphNode[] courses = new CourseGraphNode[nodes.Count];
//Cpature all courses which doesn't have any prerequisites
int endOfList = addNodesWithNoDependencies(courses, nodes, 0);
int toBeProcessed = 0;
while (toBeProcessed < courses.Length)
{
var course = courses[toBeProcessed];
//Circular dependency detected
if (course == null)
{
return(false);
}
//remove current element from dependency
List <CourseGraphNode> children = course.children;
foreach (var child in children)
{
//remove edge from removed node and child nodes
child.decrementDependencies();
}
//Add childrens that has no dependent nodes
endOfList = addNodesWithNoDependencies(courses, children, endOfList);
toBeProcessed++;
}
return(true);
}
public void addNeighbours(CourseGraphNode node)
{
if (!map.ContainsKey(node.getCourse()))
{
children.Add(node);
map.Add(node.getCourse(), node);
node.incrementDependencies();
}
}
//Get or Create Node of the graph from cache
public CourseGraphNode getOrCreateNode(int course)
{
if (!map.ContainsKey(course))
{
CourseGraphNode node = new CourseGraphNode(course);
nodes.Add(node);
map.Add(course, node);
}
return(map[course]);
}
//Add edge between start and end node and add end as neigbour of end
public void addEdge(CourseGraphNode currCourse, CourseGraphNode preRequisite)
{
preRequisite.addNeighbours(currCourse);
}