// O(E*log(N))
public static ulong[] Dijkstra(IList<N> nodes, int fromNode)
{
var dist = new ulong[nodes.Count];
var heap = new BinaryHeapWithUpdates<ulong, int>(Comparer<ulong>.Default, EqualityComparer<int>.Default);
for (int i = 0; i < dist.Length; i++)
dist[i] = ulong.MaxValue;
dist[fromNode] = 0;
heap.Insert(0, fromNode);
while (!heap.IsEmpty())
{
var min = heap.ExtractMin();
foreach (E edge in nodes[min.Value].Edges)
{
ulong d = min.Key + edge.Length;
if (d < dist[edge.ToNode])
{
if (dist[edge.ToNode] == ulong.MaxValue)
heap.Insert(d, edge.ToNode);
else
heap.UpdateKey(edge.ToNode, d);
dist[edge.ToNode] = d;
}
}
}
return dist;
}
public void UpdateKeyTest(string[] keys, string oldKey, string newKey)
{
var keyComparer = StringComparer.Ordinal;
var valueComparer = EqualityComparer<int>.Default;
var heap = new BinaryHeapWithUpdates<string, int>(keyComparer, valueComparer);
var pairs = new List<KeyValuePair<string, int>>();
foreach (var key in keys)
{
int value = key.GetHashCode();
heap.Insert(key, value);
pairs.Add(new KeyValuePair<string, int>(key, value));
}
int oldKeyIndex = Array.IndexOf(keys, oldKey);
int oldValue = pairs[oldKeyIndex].Value;
pairs[oldKeyIndex] = new KeyValuePair<string, int>(newKey, oldValue);
heap.UpdateKey(oldValue, newKey);
var expected = pairs.OrderBy(p => p.Key, keyComparer).ToArray();
for (int i = 0; i < keys.Length; i++)
{
var min = heap.ExtractMin();
Assert.Equal(expected[i], min);
}
}
// O(E*log(N))
public static Dictionary<Node, ulong> Dijkstra(Node from)
{
var dist = new Dictionary<Node, ulong>();
var heap = new BinaryHeapWithUpdates<ulong, Node>(Comparer<ulong>.Default, EqualityComparer<Node>.Default);
dist.Add(from, 0);
heap.Insert(0, from);
while (!heap.IsEmpty())
{
var min = heap.ExtractMin();
foreach (var edge in min.Value.Edges)
{
ulong newDistance = min.Key + edge.Length;
if (!dist.ContainsKey(edge.ToNode))
{
dist.Add(edge.ToNode, newDistance);
heap.Insert(newDistance, edge.ToNode);
}
else if (newDistance < dist[edge.ToNode])
{
dist[edge.ToNode] = newDistance;
heap.UpdateKey(edge.ToNode, newDistance);
}
}
}
return dist;
}
