///<summary>
/// Random graph generator for sparse graphs.
///</summary>
private void GenerateSparseGraph(Graph G)
{
G.Clear();
var index = new Dictionary <Node, int>();
int n = NodeCount;
int m = Math.Min(GetMaxEdges(), EdgeCount);
Node[] V = new Node[n];
for (int i = 0; i < n; i++)
{
V[i] = G.CreateNode();
index[V[i]] = i;
}
RandomSupport.Permutate(random, V);
int count = m;
while (count > 0)
{
int vi = random.Next(n);
Node v = V[vi];
Node w = V[random.Next(n)];
if (G.ContainsEdge(v, w) || (v == w && (!AllowSelfLoops || !AllowCycles)))
{
continue;
}
G.CreateEdge(v, w);
count--;
}
if (!AllowCycles)
{
foreach (Edge edge in G.Edges)
{
if (index[edge.Source] > index[edge.Target])
{
G.ChangeEdge(edge, edge.Target, edge.Source);
}
}
}
}
///<summary>
/// Random graph generator for dense graphs.
///</summary>
private void GenerateDenseGraph(Graph g)
{
g.Clear();
Node[] nodes = new Node[NodeCount];
for (int i = 0; i < NodeCount; i++)
{
nodes[i] = g.CreateNode();
}
RandomSupport.Permutate(random, nodes);
int m = Math.Min(GetMaxEdges(), EdgeCount);
int n = NodeCount;
int adder = (AllowSelfLoops && AllowCycles) ? 0 : 1;
bool[] edgeWanted = RandomSupport.GetBoolArray(random, GetMaxEdges(), m);
for (int i = 0, k = 0; i < n; i++)
{
for (int j = i + adder; j < n; j++, k++)
{
if (edgeWanted[k])
{
if (AllowCycles && random.NextDouble() > 0.5f)
{
g.CreateEdge(nodes[j], nodes[i]);
}
else
{
g.CreateEdge(nodes[i], nodes[j]);
}
}
}
}
}
