/// <summary>
/// Extension method to calculate shortest paths using Dijkstra's Algorithm.
/// </summary>
/// <param name="memoTable">Memoization Table</param>
/// <param name="vertex">Vertex To calculate path from</param>
/// <returns>Updated memoization table</returns>
public static MemoizationTable CalculateShortestPath(this MemoizationTable memoTable, Vertex vertex)
{
memoTable.Update(vertex, 0);
int costToCurrentVertex = 0;
// TODO: swap out infinite loop
while (true)
{
// initialise edge
Edge smallestEdgeToUnvisitedVertex = null;
// Find lowest weighted edge to an unvisited vertex from current vertex
bool changed = false;
foreach (Edge edge in vertex.GetDirectedEdges().Where(x => !x.DirectedTo.Visited))
{
memoTable.Update(edge.DirectedTo, costToCurrentVertex + edge.Weight);
if ((smallestEdgeToUnvisitedVertex == null) || (edge.Weight < smallestEdgeToUnvisitedVertex.Weight))
{
smallestEdgeToUnvisitedVertex = edge;
changed = true;
}
}
if (changed == false)
{
// All vertices visited
break;
}
// Visit nearest unvisited vertex with smallest cost
vertex = smallestEdgeToUnvisitedVertex.DirectedTo;
costToCurrentVertex += smallestEdgeToUnvisitedVertex.Weight;
}
return(memoTable);
}
