public static int GetMinCut(DirectedGraph<int> graph)
{
var nodes = new List<MergedNode>();
var edges = new List<Edge>();
foreach (var node in graph.Keys)
{
nodes.Add(new MergedNode(node));
edges.AddRange(graph.GetOutNodes(node).Select(x => new Edge(node, x)));
}
var random = new Random();
while (nodes.Count > 2)
{
var edgeIndex = random.Next(edges.Count);
var edge = edges[edgeIndex];
var node1 = nodes.First(node => node.Nodes.Contains(edge.From));
var node2 = nodes.First(node => node.Nodes.Contains(edge.To));
edges.RemoveAt(edgeIndex);
if (node1 == node2)
{
continue;
}
nodes.Remove(node1);
nodes.Remove(node2);
nodes.Add(node1.Merge(node2));
}
return GetCrossingEdgesCount(nodes[0], nodes[1], graph);
}
public static int GetCrossingEdgesCount(MergedNode node1, MergedNode node2, DirectedGraph<int> graph)
{
return node1.Nodes.Sum(n1 => node2.Nodes.Count(n2 => graph.GetOutNodes(n1).Contains(n2)));
}
