public static IList <IEnumerable <T> > GetShortestSequences <T>(T start, T end, IList <Func <T, T> > functions)
where T : IComparable <T>
{
var results = new List <IEnumerable <T> >();
var visited = new HashSet <T>();
var currentNodes = new Queue <Node <T> >();
visited.Add(start);
currentNodes.Enqueue(new Node <T>(start));
while (currentNodes.Count > 0)
{
var nextNodes = new Queue <Node <T> >();
var nextVisited = new HashSet <T>();
while (currentNodes.Count > 0)
{
var currentNode = currentNodes.Dequeue();
foreach (var function in functions)
{
T nextElement = function(currentNode.Value);
if (nextElement.CompareTo(end) > 0)
{
continue;
}
if (visited.Contains(nextElement))
{
continue;
}
var nextNode = new Node <T>(nextElement);
nextNode.Previous = currentNode;
nextVisited.Add(nextElement);
nextNodes.Enqueue(nextNode);
if (nextElement.Equals(end))
{
var sequence = new ReversedLinkedList <T>(nextNode);
results.Add(sequence.Reverse());
}
}
}
visited.UnionWith(nextVisited);
if (results.Count != 0)
{
nextNodes.Clear();
}
currentNodes = nextNodes;
}
return(results);
}
static IList <IEnumerable <T> > GetShortestSequences <T>(T start, T end, IList <Func <T, T> > operations)
where T : IComparable <T>
{
var results = new List <IEnumerable <T> >();
var visited = new HashSet <T>();
var currentWave = new Queue <Node <T> >();
visited.Add(start);
currentWave.Enqueue(new Node <T>(start));
int level = 1;
while (currentWave.Count != 0)
{
var nextWave = new Queue <Node <T> >();
var nextVisited = new HashSet <T>();
level++;
while (currentWave.Count != 0)
{
var currentNode = currentWave.Dequeue();
foreach (var operation in operations)
{
T nextElement = operation(currentNode.Value);
if (nextElement.CompareTo(end) > 0)
{
continue;
}
if (visited.Contains(nextElement))
{
continue;
}
var nextNode = new Node <T>(nextElement);
nextNode.Previous = currentNode;
nextVisited.Add(nextElement);
nextWave.Enqueue(nextNode);
if (nextElement.Equals(end))
{
var sequence = new ReversedLinkedList <T>(nextNode);
results.Add(sequence.Reverse());
}
}
}
visited.UnionWith(nextVisited);
if (results.Count != 0)
{
nextWave.Clear();
}
currentWave = nextWave;
}
//Console.WriteLine("Sequences length: {0}.", level);
return(results);
}
