MoonTools.Graph/Graph/DirectedGraph.cs

472 lines
16 KiB
C#

using System;
using System.Collections.Generic;
using System.Linq;
using Collections.Pooled;
namespace MoonTools.Graph
{
public class DirectedGraph<TNode, TEdgeData> : SimpleGraph<TNode, TEdgeData>, IUnweightedGraph<TNode, TEdgeData> where TNode : IEquatable<TNode>
{
private class SimpleCycleComparer : IEqualityComparer<IEnumerable<TNode>>
{
public bool Equals(IEnumerable<TNode> x, IEnumerable<TNode> y)
{
return x.SequenceEqual(y);
}
public int GetHashCode(IEnumerable<TNode> obj)
{
return obj.Aggregate(0, (current, next) => current.GetHashCode() ^ next.GetHashCode());
}
}
public virtual void AddEdge(TNode v, TNode u, TEdgeData edgeData)
{
BaseAddEdge(v, u, edgeData);
}
public virtual void AddEdges(params (TNode, TNode, TEdgeData)[] edges)
{
foreach (var edge in edges)
{
AddEdge(edge.Item1, edge.Item2, edge.Item3);
}
}
public void RemoveNode(TNode node)
{
CheckNodes(node);
var edgesToRemove = new PooledList<(TNode, TNode)>(ClearMode.Always);
foreach (var entry in neighbors)
{
if (entry.Value.Contains(node))
{
edgesToRemove.Add((entry.Key, node));
}
}
foreach (var edge in edgesToRemove)
{
RemoveEdge(edge.Item1, edge.Item2);
}
edgesToRemove.Dispose();
nodes.Remove(node);
neighbors.Remove(node);
}
public virtual void RemoveEdge(TNode v, TNode u)
{
CheckEdge(v, u);
neighbors[v].Remove(u);
edges.Remove((v, u));
edgeToEdgeData.Remove((v, u));
}
public IEnumerable<TNode> PreorderNodeDFS()
{
var dfsStack = new PooledStack<TNode>(ClearMode.Always);
var dfsDiscovered = new PooledSet<TNode>(ClearMode.Always);
foreach (var node in Nodes)
{
if (!dfsDiscovered.Contains(node))
{
dfsStack.Push(node);
while (dfsStack.Count > 0)
{
var current = dfsStack.Pop();
if (!dfsDiscovered.Contains(current))
{
dfsDiscovered.Add(current);
yield return current;
foreach (var neighbor in Neighbors(current))
{
dfsStack.Push(neighbor);
}
}
}
}
}
dfsStack.Dispose();
dfsDiscovered.Dispose();
}
private IEnumerable<TNode> PostorderNodeDFSHelper(PooledSet<TNode> discovered, TNode v)
{
discovered.Add(v);
foreach (var neighbor in Neighbors(v))
{
if (!discovered.Contains(neighbor))
{
foreach (var node in PostorderNodeDFSHelper(discovered, neighbor))
{
yield return node;
}
}
}
yield return v;
}
public IEnumerable<TNode> PostorderNodeDFS()
{
var dfsDiscovered = new PooledSet<TNode>(ClearMode.Always);
foreach (var node in Nodes)
{
if (!dfsDiscovered.Contains(node))
{
foreach (var thing in PostorderNodeDFSHelper(dfsDiscovered, node))
{
yield return thing;
}
}
}
}
public IEnumerable<TNode> NodeBFS()
{
var bfsQueue = new PooledQueue<TNode>(ClearMode.Always);
var bfsDiscovered = new PooledSet<TNode>(ClearMode.Always);
foreach (var node in Nodes)
{
if (!bfsDiscovered.Contains(node))
{
bfsQueue.Enqueue(node);
while (bfsQueue.Count > 0)
{
var current = bfsQueue.Dequeue();
foreach (var neighbor in Neighbors(current))
{
if (!bfsDiscovered.Contains(neighbor))
{
bfsDiscovered.Add(neighbor);
bfsQueue.Enqueue(neighbor);
yield return neighbor;
}
}
}
}
}
bfsQueue.Dispose();
bfsDiscovered.Dispose();
}
List<PooledSet<TNode>> lexicographicSets = new List<PooledSet<TNode>>();
HashSet<PooledSet<TNode>> replacedSets = new HashSet<PooledSet<TNode>>();
public IEnumerable<TNode> LexicographicBFS()
{
lexicographicSets.Add(Nodes.ToPooledSet());
while (lexicographicSets.Count > 0)
{
var firstSet = lexicographicSets[0];
var node = firstSet.First();
firstSet.Remove(node);
if (firstSet.Count == 0) { lexicographicSets.RemoveAt(0); }
yield return node;
foreach (var neighbor in Neighbors(node))
{
if (lexicographicSets.Any(set => set.Contains(neighbor)))
{
var s = lexicographicSets.Find(set => set.Contains(neighbor));
var sIndex = lexicographicSets.IndexOf(s);
PooledSet<TNode> t;
if (replacedSets.Contains(s) && sIndex > 0)
{
t = lexicographicSets[sIndex - 1];
}
else
{
t = new PooledSet<TNode>(ClearMode.Always);
lexicographicSets.Insert(sIndex, t);
replacedSets.Add(s);
}
s.Remove(neighbor);
t.Add(neighbor);
if (s.Count == 0) { lexicographicSets.Remove(s); replacedSets.Remove(s); s.Dispose(); }
}
}
}
lexicographicSets.Clear();
replacedSets.Clear();
}
public bool Cyclic()
{
return StronglyConnectedComponents().Any((scc) => scc.Count() > 1);
}
public IEnumerable<TNode> TopologicalSort()
{
return PostorderNodeDFS().Reverse();
}
List<PooledList<TNode>> sccs = new List<PooledList<TNode>>();
public IEnumerable<IEnumerable<TNode>> StronglyConnectedComponents()
{
foreach (var scc in sccs)
{
scc.Dispose();
}
sccs.Clear();
var preorder = new PooledDictionary<TNode, uint>(ClearMode.Always);
var lowlink = new PooledDictionary<TNode, uint>(ClearMode.Always);
var sccFound = new PooledDictionary<TNode, bool>(ClearMode.Always);
var sccQueue = new PooledStack<TNode>(ClearMode.Always);
uint preorderCounter = 0;
foreach (var source in Nodes)
{
if (!sccFound.ContainsKey(source))
{
var queue = new Stack<TNode>();
queue.Push(source);
while (queue.Count > 0)
{
var v = queue.Peek();
if (!preorder.ContainsKey(v))
{
preorderCounter++;
preorder[v] = preorderCounter;
}
var done = true;
var vNeighbors = Neighbors(v);
foreach (var w in vNeighbors)
{
if (!preorder.ContainsKey(w))
{
queue.Push(w);
done = false;
break;
}
}
if (done)
{
lowlink[v] = preorder[v];
foreach (var w in vNeighbors)
{
if (!sccFound.ContainsKey(w))
{
if (preorder[w] > preorder[v])
{
lowlink[v] = Math.Min(lowlink[v], lowlink[w]);
}
else
{
lowlink[v] = Math.Min(lowlink[v], preorder[w]);
}
}
}
queue.Pop();
if (lowlink[v] == preorder[v])
{
sccFound[v] = true;
var scc = new PooledList<TNode>(ClearMode.Always)
{
v
};
while (sccQueue.Count > 0 && preorder[sccQueue.Peek()] > preorder[v])
{
var k = sccQueue.Pop();
sccFound[k] = true;
scc.Add(k);
}
sccs.Add(scc);
yield return scc;
}
else
{
sccQueue.Push(v);
}
}
}
}
}
}
public IEnumerable<IEnumerable<TNode>> SimpleCycles()
{
void unblock(TNode thisnode, HashSet<TNode> blocked, Dictionary<TNode, HashSet<TNode>> B) //refactor to remove closure
{
var stack = new Stack<TNode>();
stack.Push(thisnode);
while (stack.Count > 0)
{
var node = stack.Pop();
if (blocked.Contains(thisnode))
{
blocked.Remove(thisnode);
if (B.ContainsKey(node))
{
foreach (var n in B[node])
{
if (!stack.Contains(n))
{
stack.Push(n);
}
}
B[node].Clear();
}
}
}
}
List<List<TNode>> result = new List<List<TNode>>();
var subGraph = Clone();
var sccs = new Stack<IEnumerable<TNode>>();
foreach (var scc in StronglyConnectedComponents())
{
sccs.Push(scc);
}
while (sccs.Count > 0)
{
var scc = new Stack<TNode>(sccs.Pop());
var startNode = scc.Pop();
var path = new Stack<TNode>();
path.Push(startNode);
var blocked = new HashSet<TNode>
{
startNode
};
var closed = new HashSet<TNode>();
var B = new Dictionary<TNode, HashSet<TNode>>();
var stack = new Stack<Tuple<TNode, Stack<TNode>>>();
stack.Push(Tuple.Create(startNode, new Stack<TNode>(subGraph.Neighbors(startNode))));
while (stack.Count > 0)
{
var entry = stack.Peek();
var thisnode = entry.Item1;
var neighbors = entry.Item2;
if (neighbors.Count > 0)
{
var nextNode = neighbors.Pop();
if (nextNode.Equals(startNode))
{
var resultPath = new List<TNode>();
foreach (var v in path)
{
resultPath.Add(v);
}
result.Add(resultPath);
foreach (var v in path)
{
closed.Add(v);
}
}
else if (!blocked.Contains(nextNode))
{
path.Push(nextNode);
stack.Push(Tuple.Create(nextNode, new Stack<TNode>(subGraph.Neighbors(nextNode))));
closed.Remove(nextNode);
blocked.Add(nextNode);
continue;
}
}
if (neighbors.Count == 0)
{
if (closed.Contains(thisnode))
{
unblock(thisnode, blocked, B);
}
else
{
foreach (var neighbor in subGraph.Neighbors(thisnode))
{
if (!B.ContainsKey(neighbor))
{
B[neighbor] = new HashSet<TNode>();
}
B[neighbor].Add(thisnode);
}
}
stack.Pop();
path.Pop();
}
}
subGraph.RemoveNode(startNode);
var H = subGraph.SubGraph(scc.ToArray());
var HSccs = H.StronglyConnectedComponents();
foreach (var HScc in HSccs)
{
sccs.Push(HScc);
}
}
return result.Distinct(new SimpleCycleComparer());
}
public DirectedGraph<TNode, TEdgeData> Clone()
{
var clone = new DirectedGraph<TNode, TEdgeData>();
clone.AddNodes(Nodes.ToArray());
foreach (var v in Nodes)
{
foreach (var n in Neighbors(v))
{
clone.AddEdge(v, n, EdgeData(v, n));
}
}
return clone;
}
public DirectedGraph<TNode, TEdgeData> SubGraph(params TNode[] subVertices)
{
var subGraph = new DirectedGraph<TNode, TEdgeData>();
subGraph.AddNodes(subVertices.ToArray());
foreach (var n in Nodes)
{
if (Nodes.Contains(n))
{
var neighbors = Neighbors(n);
foreach (var u in neighbors)
{
if (subVertices.Contains(u))
{
subGraph.AddEdge(n, u, EdgeData(n, u));
}
}
}
}
return subGraph;
}
public override void Clear()
{
base.Clear();
}
}
}