Question

I am creating an algorithm that is based on directed graphs. I would like a function that will grab all the nodes that are attached to a particular node.

public List<Node> GetNodesInRange(Graph graph, int Range, Node selected)
{
    var result = new List<Node>();
    result.Add(selected);
    if (Range > 0)
    {
        foreach (Node neighbour in GetNeighbours(graph, selected))
        {
            result.AddRange(GetNodesInRange(graph, Range - 1, neighbour));
        }
    }
    return result;
}

private List<Node> GetNeighbours(Graph graph, Node selected)
{
    foreach(Node node in graph.node)
    {
        if (node == selected)
        {
            GetNodesInRange(node, Range-1, /*don't know what 2 do here*/);
            //and confused all the way down

Answer 1

It depends on which kind of implementation you are using for your graph:

• edge list: you search all edges that have the specified vertex as first or second parameter to the edge
• adjacency list: the list attached to a node is already the list of nodes incident to it
• adjacency matrix: you take the column (or row) of the vertex that you chose