public static TreeNode <Point2d> MakeBfsTree(Point2d rootPt, Func <Point2d, bool> isInDomain)
{
TreeNode <Point2d> root = new TreeNode <Point2d>(rootPt);
PointSet2d alreadyIncluded = new PointSet2d();
alreadyIncluded.Add(root.value);
Point2d[] neighbors = new Point2d[8];
Queue <TreeNode <Point2d> > searchSpace = new Queue <TreeNode <Point2d> >();
searchSpace.Enqueue(root);
while (searchSpace.Count > 0)
{
var node = searchSpace.Dequeue();
SetNeighbors(node.value, ref neighbors);
for (int idx = 0; idx < neighbors.Length; idx++)
{
Point2d pt = neighbors[idx];
if (isInDomain(pt) && !alreadyIncluded.Contains(pt))
{
searchSpace.Enqueue(new TreeNode <Point2d>(pt, node));
alreadyIncluded.Add(pt);
}
}
}
return(root);
}
public static TreeNode <Point2d> MakeTreeFromContiguousSet(this PointSet2d pointSet, Func <Point2d, bool> isRoot)
{
Point2d?rootPt = null;
foreach (var pt in pointSet)
{
if (isRoot(pt))
{
rootPt = pt;
}
}
if (!rootPt.HasValue)
{
return(null);
}
else
{
return(Utils.MakeBfsTree(rootPt.Value, pt => pointSet.Contains(pt)));
}
}
public static Point2d?Bfs(Point2d start, Func <Point2d, bool> isInDomain, Func <Point2d, bool> isSatisfactory)
{
PointSet2d alreadyIncluded = new PointSet2d();
alreadyIncluded.Add(start);
Point2d[] neighbors = new Point2d[8];
Queue <Point2d> searchSpace = new Queue <Point2d>();
searchSpace.Enqueue(start);
while (searchSpace.Count > 0)
{
var current = searchSpace.Dequeue();
SetNeighbors(current, ref neighbors);
for (int idx = 0; idx < neighbors.Length; idx++)
{
Point2d pt = neighbors[idx];
if (isInDomain(pt) && !alreadyIncluded.Contains(pt))
{
if (isSatisfactory(pt))
{
return(pt);
}
else
{
searchSpace.Enqueue(pt);
alreadyIncluded.Add(pt);
}
}
}
}
return(null);
}
public static Dictionary <T, HashSet <PointSet2d> > FindContiguousSets <T>(this IField2d <T> field)
{
Dictionary <T, HashSet <PointSet2d> > categoryToSets = new Dictionary <T, HashSet <PointSet2d> >();
// At the beginning, all points are unaffiliated.
PointSet2d unaffiliated = new PointSet2d();
for (int x = 0, y = 0; y < field.Height; y += ++x / field.Width, x %= field.Width)
{
unaffiliated.Add(new Point2d(x, y));
}
Point2d[] neighbors = new Point2d[8];
for (int x = 0, y = 0; y < field.Height; y += ++x / field.Width, x %= field.Width)
{
Point2d p = new Point2d(x, y);
if (unaffiliated.Contains(p))
{
// Start a new contiguous set.
PointSet2d contiguousSet = new PointSet2d();
T key = field[p.y, p.x];
// Only points which (1) are unaffiliated and (2) have not been considered
// for this set are allowed to be candidates.
Queue <Point2d> candidates = new Queue <Point2d>();
PointSet2d considered = new PointSet2d();
candidates.Enqueue(p);
considered.Add(p);
while (candidates.Count > 0)
{
p = candidates.Dequeue();
if (Object.Equals(field[p.y, p.x], key))
{
unaffiliated.Remove(p);
contiguousSet.Add(p);
Utils.SetNeighbors(p, ref neighbors);
for (int idx = 0; idx < neighbors.Length; idx++)
{
p = neighbors[idx];
if (unaffiliated.Contains(p) && !considered.Contains(p))
{
candidates.Enqueue(p);
considered.Add(p);
}
}
}
}
HashSet <PointSet2d> sets;
if (!categoryToSets.TryGetValue(key, out sets))
{
sets = new HashSet <PointSet2d>();
categoryToSets.Add(key, sets);
}
sets.Add(contiguousSet);
}
}
return(categoryToSets);
}