started on directed graph implementation
parent
700f10f31e
commit
cb60c4ebd3
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@ -15,5 +15,6 @@
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<Content Include="Engine.cs" />
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<Content Include="attributes\Mutates.cs" />
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<Content Include="exceptions\IllegalComponentMutationException.cs" />
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<Content Include="graph\DirectedGraph.cs" />
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</ItemGroup>
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</Project>
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@ -0,0 +1,230 @@
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using System;
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using System.Collections.Generic;
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using System.Linq;
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namespace Encompass
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{
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public enum SearchSymbol
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{
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start,
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finish
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}
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public class DirectedGraph<T>
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{
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protected List<T> _vertices = new List<T>();
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protected Dictionary<T, List<T>> _edges = new Dictionary<T, List<T>>();
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public IEnumerable<T> Vertices { get { return _vertices; } }
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/*
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* GRAPH STRUCTURE METHODS
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*/
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public void AddVertex(T vertex)
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{
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if (!VertexExists(vertex))
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{
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_vertices.Add(vertex);
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_edges.Add(vertex, new List<T>());
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}
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}
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public void AddVertices(params T[] vertices)
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{
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foreach (var vertex in vertices)
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{
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AddVertex(vertex);
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}
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}
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public bool VertexExists(T vertex)
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{
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return Vertices.Contains(vertex);
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}
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public void RemoveVertex(T vertex)
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{
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if (VertexExists(vertex))
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{
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foreach (var u in Neighbors(vertex))
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{
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RemoveEdge(vertex, u);
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}
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_vertices.Remove(vertex);
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}
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}
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public void AddEdge(T v, T u)
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{
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if (VertexExists(v) && VertexExists(u))
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{
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_edges[v].Add(u);
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}
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}
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public void AddEdges(params Tuple<T, T>[] edges)
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{
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foreach (var edge in edges)
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{
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AddEdge(edge.Item1, edge.Item2);
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}
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}
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public void RemoveEdge(T v, T u)
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{
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_edges[v].Remove(u);
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}
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public IEnumerable<T> Neighbors(T vertex)
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{
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if (VertexExists(vertex))
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{
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return _edges[vertex];
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}
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else
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{
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return Enumerable.Empty<T>();
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}
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}
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/*
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* GRAPH ANALYSIS METHODS
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*/
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public Dictionary<T, Dictionary<SearchSymbol, uint>> NodeDFS()
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{
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var discovered = new HashSet<T>();
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uint time = 0;
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var output = new Dictionary<T, Dictionary<SearchSymbol, uint>>();
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foreach (var vertex in Vertices)
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{
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output.Add(vertex, new Dictionary<SearchSymbol, uint>());
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}
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Action<T> dfsHelper = null;
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dfsHelper = (T v) =>
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{
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discovered.Add(v);
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time += 1;
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output[v].Add(SearchSymbol.start, time);
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foreach (var neighbor in Neighbors(v))
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{
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if (!discovered.Contains(neighbor))
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{
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dfsHelper(neighbor);
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}
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}
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time += 1;
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output[v].Add(SearchSymbol.finish, time);
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};
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foreach (var vertex in Vertices)
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{
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if (!discovered.Contains(vertex))
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{
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dfsHelper(vertex);
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}
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}
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return output;
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}
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public IEnumerable<T> TopologicalSort()
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{
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var dfs = NodeDFS();
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var priority = new SortedList<uint, T>();
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foreach (var entry in dfs)
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{
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priority.Add(entry.Value[SearchSymbol.finish], entry.Key);
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}
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return priority.Values.Reverse();
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}
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public IEnumerable<IEnumerable<T>> StronglyConnectedComponents()
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{
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var preorder = new Dictionary<T, uint>();
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var lowlink = new Dictionary<T, uint>();
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var sccFound = new Dictionary<T, bool>();
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var sccQueue = new Stack<T>();
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var result = new List<List<T>>();
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uint preorderCounter = 0;
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foreach (var source in Vertices)
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{
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if (!sccFound.ContainsKey(source))
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{
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var queue = new Stack<T>();
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queue.Push(source);
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while (queue.Count > 0)
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{
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var v = queue.Peek();
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if (!preorder.ContainsKey(v))
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{
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preorderCounter += 1;
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preorder[v] = preorderCounter;
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}
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var done = true;
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var vNeighbors = Neighbors(v);
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foreach (var w in vNeighbors)
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{
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if (!preorder.ContainsKey(w))
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{
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queue.Push(w);
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done = false;
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break;
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}
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}
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if (done)
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{
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lowlink[v] = preorder[v];
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foreach (var w in vNeighbors)
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{
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if (!sccFound.ContainsKey(w))
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{
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if (preorder[w] > preorder[v])
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{
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lowlink[v] = Math.Min(lowlink[v], lowlink[w]);
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}
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else
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{
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lowlink[v] = Math.Min(lowlink[v], preorder[w]);
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}
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}
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}
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queue.Pop();
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if (lowlink[v] == preorder[v])
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{
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sccFound[v] = true;
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var scc = new List<T>();
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scc.Add(v);
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while (sccQueue.Count > 0 && preorder[sccQueue.Peek()] > preorder[v])
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{
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var k = sccQueue.Pop();
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sccFound[k] = true;
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scc.Add(k);
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}
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result.Add(scc);
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}
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else
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{
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sccQueue.Push(v);
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}
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}
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}
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}
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}
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return result;
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}
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}
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}
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@ -0,0 +1,216 @@
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using NUnit.Framework;
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using FluentAssertions;
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using System;
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using System.Linq;
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using Encompass;
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using System.Collections.Generic;
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namespace Tests
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{
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public class DirectedGraphTest
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{
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[Test]
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public void AddVertex()
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{
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var myGraph = new DirectedGraph<int>();
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myGraph.AddVertex(4);
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Assert.That(myGraph.Vertices, Does.Contain(4));
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}
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[Test]
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public void AddVertices()
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{
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var myGraph = new DirectedGraph<int>();
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myGraph.AddVertices(4, 20, 69);
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Assert.IsTrue(myGraph.VertexExists(4));
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Assert.IsTrue(myGraph.VertexExists(20));
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Assert.IsTrue(myGraph.VertexExists(69));
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}
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[Test]
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public void AddEdge()
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{
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var myGraph = new DirectedGraph<int>();
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myGraph.AddVertices(5, 6);
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myGraph.AddEdge(5, 6);
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Assert.That(myGraph.Neighbors(5), Does.Contain(6));
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}
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[Test]
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public void AddEdges()
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{
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var myGraph = new DirectedGraph<int>();
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myGraph.AddVertices(1, 2, 3, 4);
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myGraph.AddEdges(
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Tuple.Create(1, 2),
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Tuple.Create(2, 3),
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Tuple.Create(2, 4),
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Tuple.Create(3, 4)
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);
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Assert.That(myGraph.Neighbors(1), Does.Contain(2));
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Assert.That(myGraph.Neighbors(2), Does.Contain(3));
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Assert.That(myGraph.Neighbors(2), Does.Contain(4));
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Assert.That(myGraph.Neighbors(3), Does.Contain(4));
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Assert.That(myGraph.Neighbors(1), Does.Not.Contain(4));
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}
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[Test]
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public void RemoveEdge()
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{
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var myGraph = new DirectedGraph<int>();
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myGraph.AddVertices(1, 2, 3, 4);
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myGraph.AddEdges(
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Tuple.Create(1, 2),
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Tuple.Create(2, 3),
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Tuple.Create(2, 4),
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Tuple.Create(3, 4)
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);
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myGraph.RemoveEdge(2, 3);
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Assert.That(myGraph.Neighbors(2), Does.Not.Contain(3));
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Assert.That(myGraph.Neighbors(2), Does.Contain(4));
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}
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[Test]
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public void NodeDFS()
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{
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var myGraph = new DirectedGraph<char>();
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myGraph.AddVertices('a', 'b', 'c', 'd');
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myGraph.AddEdges(
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Tuple.Create('a', 'b'),
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Tuple.Create('a', 'c'),
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Tuple.Create('b', 'd')
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);
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var result = myGraph.NodeDFS();
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Assert.That(result['a'][SearchSymbol.start], Is.EqualTo(1));
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Assert.That(result['a'][SearchSymbol.finish], Is.EqualTo(8));
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Assert.That(result['b'][SearchSymbol.start], Is.EqualTo(2));
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Assert.That(result['b'][SearchSymbol.finish], Is.EqualTo(5));
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Assert.That(result['c'][SearchSymbol.start], Is.EqualTo(6));
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Assert.That(result['c'][SearchSymbol.finish], Is.EqualTo(7));
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Assert.That(result['d'][SearchSymbol.start], Is.EqualTo(3));
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Assert.That(result['d'][SearchSymbol.finish], Is.EqualTo(4));
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}
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[Test]
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public void TopologicalSortSimple()
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{
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var simpleGraph = new DirectedGraph<char>();
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simpleGraph.AddVertices('a', 'b', 'c', 'd');
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simpleGraph.AddEdges(
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Tuple.Create('a', 'b'),
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Tuple.Create('a', 'c'),
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Tuple.Create('b', 'a'),
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Tuple.Create('b', 'd')
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);
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Assert.That(simpleGraph.TopologicalSort(), Is.EqualTo(new char[] { 'a', 'c', 'b', 'd' }));
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}
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[Test]
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public void TopologicalSortComplex()
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{
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var complexGraph = new DirectedGraph<char>();
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complexGraph.AddVertices('a', 'b', 'c', 'd', 'e', 'f', 'g', 't', 'm');
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complexGraph.AddEdges(
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Tuple.Create('a', 'b'),
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Tuple.Create('a', 'c'),
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Tuple.Create('a', 'd'),
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Tuple.Create('b', 'f'),
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Tuple.Create('b', 'g'),
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Tuple.Create('c', 'g'),
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Tuple.Create('e', 't'),
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Tuple.Create('t', 'm')
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);
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Assert.That(
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complexGraph.TopologicalSort(),
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Is.EqualTo(new char[] { 'e', 't', 'm', 'a', 'd', 'c', 'b', 'g', 'f' })
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);
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}
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[Test]
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public void StronglyConnectedComponentsSimple()
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{
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var simpleGraph = new DirectedGraph<int>();
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simpleGraph.AddVertices(1, 2, 3);
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simpleGraph.AddEdges(
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Tuple.Create(1, 2),
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Tuple.Create(2, 3),
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Tuple.Create(3, 2),
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Tuple.Create(2, 1)
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);
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var result = simpleGraph.StronglyConnectedComponents();
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var scc = new int[] { 1, 2, 3 };
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result.Should().ContainEquivalentOf(scc);
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Assert.That(result.Count, Is.EqualTo(1));
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}
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[Test]
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public void StronglyConnectedComponentsMedium()
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{
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var mediumGraph = new DirectedGraph<int>();
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mediumGraph.AddVertices(1, 2, 3, 4);
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mediumGraph.AddEdges(
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Tuple.Create(1, 2),
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Tuple.Create(1, 3),
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Tuple.Create(1, 4),
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Tuple.Create(4, 2),
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Tuple.Create(3, 4),
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Tuple.Create(2, 3)
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);
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var result = mediumGraph.StronglyConnectedComponents();
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var sccA = new int[] { 2, 3, 4 };
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var sccB = new int[] { 1 };
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result.Should().ContainEquivalentOf(sccA);
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result.Should().ContainEquivalentOf(sccB);
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Assert.That(result.Count, Is.EqualTo(2));
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}
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[Test]
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public void StronglyConnectedComponentsComplex()
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{
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var complexGraph = new DirectedGraph<int>();
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complexGraph.AddVertices(1, 2, 3, 4, 5, 6, 7, 8);
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complexGraph.AddEdges(
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Tuple.Create(1, 2),
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Tuple.Create(2, 3),
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Tuple.Create(2, 8),
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Tuple.Create(3, 4),
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Tuple.Create(3, 7),
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Tuple.Create(4, 5),
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Tuple.Create(5, 3),
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Tuple.Create(5, 6),
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Tuple.Create(7, 4),
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Tuple.Create(7, 6),
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Tuple.Create(8, 1),
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Tuple.Create(8, 7)
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);
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var result = complexGraph.StronglyConnectedComponents();
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var sccA = new int[] { 3, 4, 5, 7 };
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var sccB = new int[] { 1, 2, 8 };
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var sccC = new int[] { 6 };
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result.Should().ContainEquivalentOf(sccA);
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result.Should().ContainEquivalentOf(sccB);
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result.Should().ContainEquivalentOf(sccC);
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Assert.That(result.Count, Is.EqualTo(3));
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}
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}
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}
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@ -5,6 +5,7 @@
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<IsPackable>false</IsPackable>
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</PropertyGroup>
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<ItemGroup>
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<PackageReference Include="FluentAssertions" Version="5.7.0" />
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<PackageReference Include="nunit" Version="3.11.0" />
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<PackageReference Include="NUnit3TestAdapter" Version="3.11.0" />
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<PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.9.0" />
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@ -13,5 +14,6 @@
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<ItemGroup>
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<ProjectReference Include="..\src\encompass-cs.csproj" />
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<Content Include="EngineTest.cs" />
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<Content Include="DirectedGraphTest.cs" />
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</ItemGroup>
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</Project>
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