public void AlotOfElements()
{
var queue = new DijkstraPriorityQueue();
queue.Insert(new DijkstraNode("a"), 2);
queue.Insert(new DijkstraNode("b"), 2);
queue.Insert(new DijkstraNode("c"), 1);
queue.Insert(new DijkstraNode("d"), 1);
queue.Insert(new DijkstraNode("e"), 1);
queue.Insert(new DijkstraNode("f"), 1);
queue.Insert(new DijkstraNode("g"), 3);
queue.Insert(new DijkstraNode("h"), 2);
queue.Insert(new DijkstraNode("i"), 3);
queue.Insert(new DijkstraNode("j"), 1);
queue.Insert(new DijkstraNode("k"), 2);
queue.Insert(new DijkstraNode("l"), 3);
queue.Insert(new DijkstraNode("m"), 2);
queue.Insert(new DijkstraNode("n"), 3);
queue.Insert(new DijkstraNode("o"), 1);
queue.Insert(new DijkstraNode("p"), 2);
queue.Insert(new DijkstraNode("q"), 0);
queue.Insert(new DijkstraNode("r"), 1);
var nodes = new List <string>();
while (queue.Size != 0)
{
var(node, priority) = queue.ExtractMin();
nodes.Add(node.Name);
}
var actual = string.Join(" ", nodes);
Assert.AreEqual("q c d e f j o r a b h k m p g i l n", actual);
}
/// <summary>
/// Dijkstra initialization
/// </summary>
/// <param name="graph"> source graph </param>
/// <param name="source"> source node </param>
/// <param name="distances"> empty priority queue </param>
private void Initialize
(Graph graph, DijkstraNode source, DijkstraPriorityQueue distances)
{
source.Distance = 0;
var vertices = graph.AdjDict.GetVertices();
foreach (var v in vertices)
{
distances.Insert(v, v.Distance);
}
}
/// <summary>
/// find shortest distance to vertice v
/// between known distance (v.Distance)
/// and from u across edge (u, v)
/// </summary>
/// <param name="u"> source node </param>
/// <param name="v"> adjacent node </param>
/// <param name="weight"> weith of edge between u and v </param>
/// <param name="queue"> pririty queue with Dijkstra nodes </param>
private void Relax(DijkstraNode u, DijkstraNode v, int weight,
DijkstraPriorityQueue queue)
{
var distanceThroughU = u.Distance + weight;
if (distanceThroughU < v.Distance)
{
v.Distance = distanceThroughU;
v.Prev = u;
queue.ChangePriority(v, distanceThroughU);
}
}
/// <summary>
/// Call Dijkstra algorithm
/// </summary>
/// <param name="graph"> source graph </param>
/// <param name="source"> the node
/// from which we look for the shortest paths </param>
/// <returns> graph with filled "distances" and "prevs" of every node </returns>
public Graph Execute(Graph graph, DijkstraNode source)
{
var priorityQueue = new DijkstraPriorityQueue();
Initialize(graph, source, priorityQueue);
while (priorityQueue.Size != 0)
{
var start = priorityQueue.ExtractMin();
var adjNodes = graph.AdjDict[start.node];
foreach (var(node, weight) in adjNodes)
{
Relax(start.node, node, weight, priorityQueue);
}
}
return(graph);
}
public void EqualPriorities()
{
var queue = new DijkstraPriorityQueue();
queue.Insert(new DijkstraNode("a"), 1);
queue.Insert(new DijkstraNode("b"), 1);
queue.Insert(new DijkstraNode("c"), 1);
queue.Insert(new DijkstraNode("d"), 1);
var nodes = new List <string>();
while (queue.Size != 0)
{
var(node, priority) = queue.ExtractMin();
nodes.Add(node.Name);
}
var actual = string.Join(" ", nodes);
Assert.AreEqual("a b c d", actual);
}
// This puts the start node into the queue
protected internal virtual void InitQueue()
{
Queue = new DijkstraPriorityQueueFibonacciImpl <CostType>(outerInstance.CostComparator);
Queue.insertValue(StartNode, outerInstance.StartCost);
MySeen[StartNode] = outerInstance.StartCost;
}
