private IEnumerable <NodeToNodeEdge> GetDistinctEdges()
{
var distinctEdges = new List <NodeToNodeEdge>();
var nodes = _mapProvider.GetAllNodes();
foreach (var node in nodes)
{
var edges = node.Edges
.Select(e => new NodeToNodeEdge(node.Id, e.EndNode));
foreach (var edge in edges)
{
if (!distinctEdges.Any(e => e.Equals(edge)))
{
distinctEdges.Add(edge);
}
}
}
return(distinctEdges);
}
/// <summary>
/// Returns a dictionary where each Key is a Node on the map with its closest predecessor as value.
/// </summary>
private Dictionary <Node, Node> FindAllPaths(int startNodeId)
{
Node startNode = _mapProvider.GetNode(startNodeId);
// Initialize sets ready for walking
var queue = new List <Node>()
{
startNode
};
var distances = new Dictionary <Node, int>()
{
{ startNode, 0 }
};
var predecessors = new Dictionary <Node, Node>();
var unvisited = _mapProvider.GetAllNodes()
.Except(new [] { startNode }).ToList();
IEnumerable <Edge> GetUnvisitedEdges(Node node) =>
node.Edges
.Where(edge => unvisited.Any(visitedNode => edge.EndNode == visitedNode.Id));
Node GetNearestNodeInQueue() => queue.OrderBy(node => distances[node])
.First();
while (queue.Any())
{
var currentNode = GetNearestNodeInQueue();
queue.Remove(currentNode);
var currentDistance = distances[currentNode];
var unvisitedEdges = GetUnvisitedEdges(currentNode);
foreach (var edge in unvisitedEdges)
{
var unvisitedEndPoint = _mapProvider.GetNode(edge.EndNode);
queue.Add(unvisitedEndPoint);
distances.Add(unvisitedEndPoint, currentDistance + edge.Distance);
predecessors.Add(unvisitedEndPoint, currentNode);
unvisited.Remove(unvisitedEndPoint);
}
}
return(predecessors);
}
