private static IEnumerable<Course> CreateBasicUnsortedList()
{
var a = new Course("B", new Course("A", null));
var b = new Course("E", new Course("C", new Course("D", null)));
var c = new Course("F", new Course("A", null));
return new[] { a, b, c };
}
private static IEnumerable<Course> CreateComplexUnsortedList()
{
var a = new Course("B", new Course("A", null));
var b = new Course("E", new Course("C", new Course("D", new Course("G", null))));
var c = new Course("F", new Course("A", null));
var d = new Course("H", new Course("D", null));
return new[] { a, b, c, d };
}
private static void Visit(Course course, Func<Course, Course> getDependencies, StringBuilder sorted, Dictionary<string, bool> visited)
{
if (visited.ContainsKey(course.Title)) return;
visited[course.Title] = true;
var dependency = getDependencies(course);
if (dependency != null) Visit(dependency, getDependencies, sorted, visited);
if (sorted.Length == 0) sorted.Append(course.Title);
else sorted.Append(", " + course.Title);
}
public static void AddCourse(this List<Course> courses, Course course)
{
if (courses.Count > 0)
{
foreach (var rootCourse in courses)
{
if (course.Dependency != null && rootCourse.Title == course.Dependency.Title)
{
course.Dependency = rootCourse;
courses.Remove(rootCourse);
courses.Add(course);
return;
}
var courseInChain = rootCourse;
while (courseInChain.Dependency != null)
{
if (course.Dependency == null)
{
if (course.Title == courseInChain.Title || course.Title == courseInChain.Dependency.Title) return;
}
else
{
if (course.Title == courseInChain.Dependency.Title && courseInChain.Dependency.Dependency == null)
{
courseInChain.Dependency = course;
return;
}
}
courseInChain = courseInChain.Dependency;
}
if (course.Title == courseInChain.Title && course.Dependency != null)
{
courseInChain.Dependency = new Course(course.Dependency.Title, null);
return;
}
}
}
courses.Add(course);
}
private Course[] CreateComplexCyclicList()
{
var a = new Course("A", new Course("C", new Course("B", new Course("A", null))));
return new[] { a };
}