public static IEnumerable <Course> DepthFirstTraversal(this Courses courses, Course start)
{
var visited = new HashSet <Course>();
var stack = new Stack <Course>();
stack.Push(start);
while (stack.Count != 0)
{
var current = stack.Pop();
if (!visited.Add(current))
{
continue;
}
yield return(current);
var neighbours = courses.GetAdjacentCoursesFromCourseName(current.Name)
.Where(n => !visited.Contains(n));
// If you don't care about the left-to-right order, remove the Reverse
foreach (var neighbour in neighbours.Reverse())
{
stack.Push(neighbour);
}
}
}
