public T Compute <T>(IDPAlgorithm <T> algorithm, TDNode parent, Dictionary <Tuple <TDNode, TDNode>, T> lookup)
{
T result;
if (lookup.TryGetValue(Tuple.Create(this, parent), out result))
{
return(result);
}
IEnumerable <TDNode> children = Adj.Where((n) => n != parent);
if (!children.Any())
{
result = algorithm.Introduce(this, Bag, algorithm.Leaf(ParentDecomposition.Width));
}
else
{
TDNode first = children.First();
result = AdjustBag(algorithm, first, first.Compute(algorithm, this, lookup));
foreach (TDNode next in children.Skip(1))
{
result = algorithm.Join(this, result, AdjustBag(algorithm, next, next.Compute(algorithm, this, lookup)));
}
}
// Only cache if the result might be reused, prevents caching in all nodes of a long chain
if (parent == null || parent.Adj.Count() > 2)
{
lookup[Tuple.Create(this, parent)] = result;
}
return(result);
}
public T Compute <T>(IDPAlgorithm <T> algorithm, TDNode parent)
{
VertexSubset.ClearLookup();
// Note: through preprocessing, certain subtrees might have become empty. Do not consider.
IEnumerable <TDNode> children = Adj.Where((n) => n != parent && n.Subtree.Any());
if (children.Count() == 0)
{
return(algorithm.IntroduceEdges(algorithm.Introduce(this, Bag, algorithm.Leaf(ParentDecomposition.Width)), introduceEdges));
}
if (children.Count() == 1)
{
TDNode child = children.First();
Vertex[] toForget = child.Bag.Where((v) => !this.BagContains(v)).OrderBy((v) => v.Adj.Where((w) => BagContains(w.To)).Count()).Reverse().ToArray();
Vertex[] toIntroduce = this.Bag.Where((v) => !child.BagContains(v)).ToArray();
if (toIntroduce.Length > 0)
{
return(algorithm.IntroduceEdges(algorithm.Introduce(this, toIntroduce, child.Compute(algorithm, this)), introduceEdges));
}
if (toForget.Length > 0)
{
return(algorithm.IntroduceEdges(algorithm.Forget(this, toForget, child.Compute(algorithm, this)), introduceEdges));
}
// No change?
return(algorithm.IntroduceEdges(child.Compute(algorithm, this), introduceEdges));
}
if (children.Count() > 2)
{
throw new Exception("TD not preprocessed!");
}
TDNode left = children.ElementAt(0), right = children.ElementAt(1);
return(algorithm.IntroduceEdges(algorithm.Join(this, IntroduceIfNecessary(algorithm, left, left.Compute(algorithm, this)), IntroduceIfNecessary(algorithm, right, right.Compute(algorithm, this))), introduceEdges));
}