C# Graph Traversal

Question

This algorithm does a great job of traversing the nodes in a graph.

Dictionary visited = new Dictionary();

Queue         


        

Answer 1

Keep track of the predecessor nodes. In the easiest implementation, this is a dictionary, and usually denoted as π in pseudo-codes:

Dictionary visited = new Dictionary();
Dictionary π = new Dictionary();

Queue worklist = new Queue();

visited.Add(this, false);

worklist.Enqueue(this);

while (worklist.Count != 0)
{
    Node node = worklist.Dequeue();

    foreach (Node neighbor in node.Neighbors)
    {
        if (!visited.ContainsKey(neighbor))
        {
            visited.Add(neighbor, false);
            π.Add(neighbor, node);
            worklist.Enqueue(neighbor);
        }
    }
}

Then you can iterate through these predecessors to backtrack the path from any node, say e:

while (π[e] != null) {
    Console.WriteLine(e);
    e = π[e];
}