private void Visit(EdgeWeightedGraph g, int v)
{
marked[v] = true;
foreach (var e in g.Adj(v))
{
int w = e.Other(v);
if (marked[w])
{
continue;
}
if (e.Weight < distTo[w])
{
edgeTo[w] = e;
distTo[w] = e.Weight;
if (pq.Contains(w))
{
pq.ChangeKey(w, distTo[w]);
}
else
{
pq.Insert(w, distTo[w]);
}
}
}
}
private void Scan(EdgeWeightedGraph G, int v)
{
_marked[v] = true;
foreach (Edge e in G.Adj(v))
{
int w = e.Target(v);
if (_marked[w])
{
continue;
}
if (e.Weight() < _distTo[w])
{
_distTo[w] = e.Weight();
_edgeTo[w] = e;
if (_pq.Contains(w))
{
_pq.ChangeKey(w, _distTo[w]);
}
else
{
_pq.Insert(w, _distTo[w]);
}
}
}
}
List <List <int> > GetMST()
{
var size = nodes.NodeList.Count;
var parents = new int[size];
var weights = new float[size];
var marked = new bool[size];
var pq = new IndexMinPriorityQueue <float>(size);
for (var x = 1; x < size; x++)
{
weights[x] = float.MaxValue;
}
weights[0] = 0;
pq.Insert(0, 0);
while (!pq.IsEmpty())
{
int v = pq.DeleteMin();
marked[v] = true;
for (var x = 0; x < size; x++)
{
if (x != v && !marked[x])
{
var distance = Vector2.Distance(nodes.NodeList[v], nodes.NodeList[x]);
if (distance < weights[x])
{
weights[x] = distance;
parents[x] = v;
if (pq.Contains(x))
{
pq.ChangeKey(x, distance);
}
else
{
pq.Insert(x, distance);
}
}
}
}
}
var result = GetAdjacencyLists(size);
for (var x = 1; x < parents.Length; x++)
{
var target = parents[x];
result[x].Add(target);
result[target].Add(x);
}
return(result);
}
public void ChangeKey_WhenIndexIsInQueue_WillChangeOldKeyToNewKey()
{
IndexMinPriorityQueue <double> queue = new IndexMinPriorityQueue <double>(10);
queue.Insert(4, 12.5);
queue.Insert(3, 40.12);
queue.Insert(7, 4.3);
queue.Insert(2, 162.75);
double newKey = 5.54;
queue.ChangeKey(3, newKey);
double keyAtIndex = queue.KeyAt(3);
Assert.AreEqual(newKey, keyAtIndex);
}
private void Relax(EdgeWeightedDigraph g, int v)
{
foreach (var e in g.Adj(v))
{
int w = e.To;
if (distTo[w] > distTo[v] + e.Weight)
{
distTo[w] = distTo[v] + e.Weight;
edgeTo[w] = e;
if (pq.Contains(w))
{
pq.ChangeKey(w, distTo[w]);
}
else
{
pq.Insert(w, distTo[w]);
}
}
}
}
