构建一个从头开始使用Dijkstras alg的图表控件。我试图了解这个算法，在网上搜索。我想我终于明白了，但是我的代码无法正常工作。希望有人可以看一看，看看他们是否知道与它有什么关系......
我会粘贴三种方法，因为我认为这是可能需要的所有方法。
对于初学者，我会说我创建了自己的Vertex数据类型。它包含节点的ID，X和Y，状态字符串，以及也是顶点数据类型的父节点和整数的距离。
//function to populate lists with all the vertices on the graph
private List<Vertex> getNodes()
{
myVertices.Clear();
//get all non-dg nodes in list
for (int i = 0; i < chtGraph.Series[0].Points.Count; i++)
{
Vertex vertice = new Vertex(chtGraph.Series[0].Points[i]["ID"], (float)chtGraph.Series[0].Points[i].XValue, (float)chtGraph.Series[0].Points[i].YValues[0], "UNVISITED", Convert.ToInt32(chtGraph.Series[0].Points[i].Label), double.PositiveInfinity, null);
myVertices.Insert(i, vertice);
}
//get all dg nodes in list
for (int i = 0; i < chtGraph.Series[1].Points.Count; i++)
{
Vertex vertice = new Vertex(chtGraph.Series[1].Points[i]["ID"], (float)chtGraph.Series[1].Points[i].XValue, (float)chtGraph.Series[1].Points[i].YValues[0], "UNVISITED", Convert.ToInt32(chtGraph.Series[1].Points[i].Label), double.PositiveInfinity, null);
myVertices.Insert(i, vertice);
}
return myVertices;
}
//function to return to a list all the adjacents for a specified node. Excludes parent node
private List<Vertex> checkAdjacents(Vertex node, int intTransPower)
{
List<Vertex> Adjacents = new List<Vertex>();
int distance;
for (int i = 0; i < myVertices.Count; i++)
{
if (node.id != myVertices[i].id)
{
distance = calcDistance(node.x, node.y, myVertices[i].x, myVertices[i].y);
if (distance <= intTransPower)
{
if (rdbTotalLength.Checked)
{
myVertices[i].distance = distance;
}
else if (rdbPathEnergy.Checked)
{
myVertices[i].distance = getCost(node, myVertices[i]);
}
else
{
myVertices[i].distance = 1;
}
myVertices[i].parent = node;
Adjacents.Add(myVertices[i]);
foreach (Vertex p in openList)
{
if (myVertices[i].id == p.id)
{
p.distance = myVertices[i].distance;
p.parent = myVertices[i].parent;
}
}
}
}
}
return Adjacents;
}
这里是dijkstras ....目前工作不正常，我无法理解。
private void dijkstra(Vertex start, Vertex end)
{
openList.Clear();
//populate two lists with all the nodes in the graph
openList = getNodes();
myVertices = getNodes();
//adjacents list for each vertex visited
List<Vertex> adjacents = new List<Vertex>();
//final list that is populated with the final path of vertices
List<Edge> shortestPath = new List<Edge>();
//used in calculating adjacent nodes. If distance is greater than transpower, then nodes are not connected
int intTransPower = Convert.ToInt32(txtTransPower.Text);
//set current vertex as the starting node
Vertex current = start;
//set initially to false
bool pathFound = false;
//find the starting node from the list of all vertices. Set it's distance to 0
foreach (Vertex p in openList)
{
if (p.id == current.id)
{
p.status = current.status;
p.distance = 0;
}
}
foreach (Vertex p in myVertices)
{
if (p.id == current.id)
{
p.status = current.status;
p.distance = 0;
}
}
//reorder the list to bring the starting node to the first element
openList = openList.OrderBy(h => h.distance).ToList();
//openList.Add(current);
//this.insert(openList, current, true);
// Repeat while the openlist is not empty and you haven't reached the end
while (openList.Count > 0)
{
//remove node at element 0. Sorted by smallest distance so it always gets removed first
current = openList[0];
openList.RemoveAt(0);
//if the current node = the ending node, then we have found the path. Break loop and build the final path.
if (current.id == end.id)
{
pathFound = true;
break;
}
//collect up all the adjacent nodes for the current vertex
//does NOT include the current vertex we are on
adjacents = checkAdjacents(current, intTransPower);
foreach (Vertex v in adjacents)
{
float alt = (float)current.distance + calcDistance(current.x, current.y, v.x, v.y);
Convert.ToInt32(alt);
if (alt < v.distance)
{
v.distance = alt;
v.parent = current;
for (int i = 0; i < openList.Count; i++)
{
if (v.id == openList[i].id)
{
openList[i].distance = alt;
openList[i].parent = current;
}
}
}
}
openList = openList.OrderBy(h => h.distance).ToList();
}
if (pathFound)
{
// collect path
this.foundPath.Clear();
Vertex last = current;
while (current != start && current != null)
{
this.foundPath.Add(current);
if (current.parent == last)
break;
last = current;
current = current.parent;
}
this.foundPath.Add(current);
}
}
答案 0 :(得分：-1)
我有这种方法，但它是更大实现的一部分：
public static IDigraph DijkstrasAlgorithm(IDigraph g, int s)
{
//Collect number of vertices
int num1 = g.NumberOfVertices;
//create an array for vertices
Entry[] entryArray1 = new Graphos.Algorithms.Entry[num1];
//for each vertice create new instance for entry of edges
for (int num2 = 0; num2 < num1; num2++)
{
entryArray1[num2] = new Graphos.Algorithms.Entry(false, 0x7fffffff, 0x7fffffff);
}
//set vertice origin with distance 0.
entryArray1[s].distance = 0;
//create a list for edges
PriorityQueue queue1 = new BinaryHeap(g.NumberOfEdges);
//create initial nodes in edges list
queue1.Enqueue(new Association(0, g.GetVertex(s)));
//while list is not empty
while (!queue1.IsEmpty)
{
//creates an association
Association association1 = (Association)queue1.DequeueMin();
//attributes the vertice
IVertex vertex1 = (IVertex)association1.Value;
//if connection is known
if (!entryArray1[vertex1.Number].known)
{
//checks as known
entryArray1[vertex1.Number].known = true;
//foreach edge founded
foreach (Edge edge1 in vertex1.EmanatingEdges)
{
//creates the vertex that is being used
IVertex vertex2 = edge1.MateOf(vertex1);
//catches the weight since vertice in link
int num3 = entryArray1[vertex1.Number].distance + ((int)edge1.Weight);
//se o peso da ponte for menor que o peso maximo
if (entryArray1[vertex2.Number].distance > num3)
{
//Peso maximo é atualizado para o peso da ponte
entryArray1[vertex2.Number].distance = num3;
//Define o vértice vizinho
entryArray1[vertex2.Number].predecessor = vertex1.Number;
//adiciona o vértice com seu vizinho e o peso entre eles na lista
queue1.Enqueue(new Association(num3, vertex2));
}
}
}
}
//Á este ponto, todas as associações foram feitas
//Cria o objeto grafo como uma lista baseado no numero de vertices
IDigraph digraph1 = new DigraphAsLists(num1);
//Para cada vértice
for (int num4 = 0; num4 < num1; num4++)
{
//adiciona o vertice da lista no grafo
digraph1.AddVertex(num4, entryArray1[num4].distance);
}
//para cada vertice
for (int num5 = 0; num5 < num1; num5++)
{
//Se não for o ponto de origem
if (num5 != s)
{
//adiciona a aresta(origem,destino baseado no vizinho)
digraph1.AddEdge(num5, entryArray1[num5].predecessor);
}
}
//retorna o grafo
return digraph1;
}