public static Dictionary <int, int> Levit(Generate.Graph g, int s)
{
var d = g.ToDictionary(pair => pair.Key, pair => int.MaxValue);
d[s] = 0;
var computed = new SortedSet <int>();
var unknown = new SortedSet <int>();
var enqueued = new SortedSet <int>();
var todo = new Queue <int>();
var todoPriority = new Queue <int>();
foreach (var v in g.Keys.Where(gValue => gValue != s))
{
unknown.Add(v);
d[v] = int.MaxValue;
}
computed.Add(s);
todo.Enqueue(s);
enqueued.Add(s);
while (todo.Count > 0 || todoPriority.Count > 0)
{
var u = todoPriority.Count > 0 ? todoPriority.Dequeue() : todo.Dequeue();
enqueued.Remove(u);
foreach (var v in g[u].Keys)
{
if (u == v)
{
continue;
}
var altDistance = d[u] + g[u][v];
var shouldRelax = d[v] > altDistance;
if (unknown.Contains(v))
{
unknown.Remove(v);
todo.Enqueue(v);
d[v] = altDistance;
continue;
}
if (!shouldRelax)
{
continue;
}
d[v] = altDistance;
if (!enqueued.Contains(v))
{
todoPriority.Enqueue(v);
}
}
}
return(d);
}
public static Dictionary <int, int> Dijkstra(Generate.Graph g, int s)
{
var unvisited = new SortedSet <int>();
var d = new Dictionary <int, int>();
foreach (var v in g.Keys)
{
unvisited.Add(v);
d[v] = int.MaxValue;
}
d[s] = 0;
while (unvisited.Count > 0)
{
var v = d.Keys.Where(key => unvisited.Contains(key)).OrderBy(key => d[key]).First();
unvisited.Remove(v);
if (d[v] == int.MaxValue)
{
continue;
}
foreach (var(u, w) in g[v])
{
if (!unvisited.Contains(u))
{
continue;
}
var altDistance = d[v] + w;
if (d[u] > altDistance)
{
d[u] = altDistance;
}
}
}
return(d);
}
