public static IEnumerable <int> BreathFirstSearch(IEnumerable <int> starts, AdjacencyListGraph <long> graph)
{
var visited = new SearchData <bool>(graph.Size(), false);
var queue = new Queue <int>();
foreach (var start in starts)
{
visited.SetValue(start, false);
queue.Enqueue(start);
}
while (queue.Any())
{
var current = queue.Dequeue();
foreach (var neighbor in graph.NeighborIndexes(current).Where(i => i != current))
{
if (visited.Visited(neighbor))
{
continue;
}
queue.Enqueue(neighbor);
visited.SetValue(neighbor, true);
}
}
var visitedIndexes = visited.Values
.Select((v, i) => new { Visited = v, Index = i })
.Where(x => x.Visited)
.Select(x => x.Index);
return(visitedIndexes);
}
private AdjacencyListGraph ToAdjacencyGraph(Action <AdjacencyListGraph, Edge> addEdge)
{
var line0 = ParseIntPair(_inputs[0]);
var verticeCount = line0.Item1;
var edgeCount = line0.Item2;
var graph = new AdjacencyListGraph(verticeCount);
foreach (var edge in Enumerable.Range(1, edgeCount).Select(i => ParseEdge(_inputs[i])))
{
addEdge(graph, edge);
}
_lineCursor = edgeCount + 1;
return(graph);
}
private static BellmanFordResult ShortestPath(int start, int size, List <Edge <long> > edges)
{
var g = new AdjacencyListGraph <long>(size);
foreach (var edge in edges)
{
g.AddDirectedEdge(edge);
}
var result = BellmanFord(start, size, edges);
var negative = edges
.Where(e => ShouldRelax(e.Left, e.Right, e.Weight, result).Item1)
.Select(e => e.Right)
.ToList();
foreach (var i in BreathFirstSearch(negative, g))
{
result.Distance.SetValue(i, NegativeInfinity);
}
return(result);
}
public Dijkstras(AdjacencyListGraph <long> g)
{
_graph = g;
}
public DijkstrasAlgorithm(AdjacencyListGraph g)
{
_graph = g;
}