Most efficient way of creating tree from adjacency list
- by Jeff Meatball Yang
I have an adjacency list of objects (rows loaded from SQL database with the key and it's parent key) that I need to use to build an unordered tree. It's guaranteed to not have cycles.
This is taking wayyy too long (processed only ~3K out of 870K nodes in about 5 minutes). Running on my workstation Core 2 Duo with plenty of RAM.
Any ideas on how to make this faster?
public class StampHierarchy {
private StampNode _root;
private SortedList<int, StampNode> _keyNodeIndex;
// takes a list of nodes and builds a tree
// starting at _root
private void BuildHierarchy(List<StampNode> nodes)
{
Stack<StampNode> processor = new Stack<StampNode>();
_keyNodeIndex = new SortedList<int, StampNode>(nodes.Count);
// find the root
_root = nodes.Find(n => n.Parent == 0);
// find children...
processor.Push(_root);
while (processor.Count != 0)
{
StampNode current = processor.Pop();
// keep a direct link to the node via the key
_keyNodeIndex.Add(current.Key, current);
// add children
current.Children.AddRange(nodes.Where(n => n.Parent == current.Key));
// queue the children
foreach (StampNode child in current.Children)
{
processor.Push(child);
nodes.Remove(child); // thought this might help the Where above
}
}
}
}
public class StampNode {
// properties: int Key, int Parent, string Name, List<StampNode> Children
}
