149 lines
4.5 KiB
C#
149 lines
4.5 KiB
C#
using FLCompanionByDvurechensky.Data;
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using System.Collections.Generic;
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/// <summary>
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/// TODO: работает не корректно
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/// Алгоритм Дейкстры
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/// </summary>
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public class Dijkstra
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{
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Graph graph;
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List<GraphVertexInfo> infos;
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/// <summary>
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/// Конструктор
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/// </summary>
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/// <param name="graph">Граф</param>
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public Dijkstra(Graph graph)
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{
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this.graph = graph;
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}
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/// <summary>
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/// Инициализация информации
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/// </summary>
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void InitInfo()
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{
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infos = new List<GraphVertexInfo>();
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foreach (var v in graph.Vertices)
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{
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infos.Add(new GraphVertexInfo(v));
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}
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}
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/// <summary>
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/// Получение информации о вершине графа
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/// </summary>
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/// <param name="v">Вершина</param>
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/// <returns>Информация о вершине</returns>
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GraphVertexInfo GetVertexInfo(GraphVertex v)
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{
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if (v == null) return null;
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foreach (var i in infos)
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{
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if (i.Vertex.Name.Contains(v.Name))
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{
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return i;
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}
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}
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return null;
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}
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/// <summary>
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/// Поиск непосещенной вершины с минимальным значением суммы
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/// </summary>
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/// <returns>Информация о вершине</returns>
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public GraphVertexInfo FindUnvisitedVertexWithMinSum()
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{
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var minValue = int.MaxValue;
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GraphVertexInfo minVertexInfo = null;
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foreach (var i in infos)
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{
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if (i.IsUnvisited && i.EdgesWeightSum < minValue)
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{
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minVertexInfo = i;
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minValue = i.EdgesWeightSum;
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}
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}
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return minVertexInfo;
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}
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/// <summary>
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/// Поиск кратчайшего пути по названиям вершин
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/// </summary>
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/// <param name="startName">Название стартовой вершины</param>
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/// <param name="finishName">Название финишной вершины</param>
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/// <returns>Кратчайший путь</returns>
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public string FindShortestPath(string startName, string finishName)
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{
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return FindShortestPath(graph.FindVertex(startName), graph.FindVertex(finishName));
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}
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/// <summary>
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/// Поиск кратчайшего пути по вершинам
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/// </summary>
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/// <param name="startVertex">Стартовая вершина</param>
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/// <param name="finishVertex">Финишная вершина</param>
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/// <returns>Кратчайший путь</returns>
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public string FindShortestPath(GraphVertex startVertex, GraphVertex finishVertex)
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{
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InitInfo();
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var first = GetVertexInfo(startVertex);
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first.EdgesWeightSum = 0;
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while (true)
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{
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var current = FindUnvisitedVertexWithMinSum();
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if (current == null)
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{
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break;
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}
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SetSumToNextVertex(current);
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}
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return GetPath(startVertex, finishVertex);
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}
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/// <summary>
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/// Вычисление суммы весов ребер для следующей вершины
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/// </summary>
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/// <param name="info">Информация о текущей вершине</param>
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void SetSumToNextVertex(GraphVertexInfo info)
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{
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info.IsUnvisited = false;
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foreach (var e in info.Vertex.Edges)
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{
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var nextInfo = GetVertexInfo(e.ConnectedVertex);
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var sum = info.EdgesWeightSum + e.EdgeWeight;
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if (sum < nextInfo.EdgesWeightSum)
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{
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nextInfo.EdgesWeightSum = sum;
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nextInfo.PreviousVertex = info.Vertex;
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}
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}
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}
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/// <summary>
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/// Формирование пути
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/// </summary>
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/// <param name="startVertex">Начальная вершина</param>
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/// <param name="endVertex">Конечная вершина</param>
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/// <returns>Путь</returns>
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string GetPath(GraphVertex startVertex, GraphVertex endVertex)
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{
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var path = endVertex.ToString();
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while (startVertex != endVertex)
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{
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if(endVertex == null) return path;
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endVertex = GetVertexInfo(endVertex).PreviousVertex;
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if(endVertex != null)
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path = endVertex.ToString() + " = " + path;
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}
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return path;
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}
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} |