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Find node when moving tree

I want to implement a method that will allow me to find a node in a tree. The way I do this recursively uses global variables to know when to stop.

I have a class:

class Node    // represents a node in the tree
{ 
     // constructor
     public Node() {
          Children = new List<Node>();
     }

     public List<Node> Children; 
     public string Name;
     public string Content;            
}

And the method that I have now:

    private bool IsNodeFound = false; // global variable that I use to decide when to stop

    // method to find a particular node in the tree
    private void Find(Node node, string stringToFind, Action<Node> foundNode)
    {
        if(IsNodeFound)
           return;

        if (node.Content.Contains(stringToFind)){
            foundNode(node); 
            IsNodeFound =true;               
        }

        foreach (var child in node.Children)
        {
            if (child.Content.Contains(stringToFind)){
                foundNode(node);
                IsNodeFound =true;               
            }

            Find(child, stringToFind, foundNode);
        }

    }

, and the way I use the Find method looks like this:

   // root is a node that contain children and those children also contain children
   // root is the "root" of the tree
   IsNodeFound =false;
   Node nodeToFind = null;
   Find(root, "some string to look for", (x)=> nodeToFind=x);

So my question is how can I make this method more elegant. I will like the method signature:

   public Node FindNode(Node rootNode);

I think this is redundant, what I'm doing, and probably the best way to create this method. Or perhaps I could modify the node class so that I can achieve the same result with the linq query.

+5
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6 answers

I would do it like this:

node ( , Node):

public IEnumerable<Node> GetNodeAndDescendants() // Note that this method is lazy
{
     return new[] { this }
            .Concat(Children.SelectMany(child => child.GetNodeAndDescendants()));    
}

LINQ:

var foundNode = rootNode.GetNodeAndDescendants()
                        .FirstOrDefault(node => node.Content.Contains(stringToFind));

if(foundNode != null)
{
    DoSomething(foundNode);
}
+10

, Linq, :

public Node Find(string stringToFind)
{
    // find the string, starting with the current instance
    return Find(this, stringToFind);
}

// Search for a string in the specified node and all of its children
public Node Find(Node node, string stringToFind)
{
    if (node.Content.Contains(stringToFind))
        return node;

    foreach (var child in node.Children) 
    { 
        var result = Find(child, stringToFind);
        if (result != null)
            return result;
    }

    return null;
}
+9

( , ):

Node FindNode1( Node rootNode, string stringToFind ) {
    if( rootNode.Content == stringToFind ) return rootNode;
    foreach( var child in rootNode.Children ) {
        var n = FindNode1( child, stringToFind );
        if( n != null ) return n;
    }
    return null;
}

, , :

Node FindNode2( Node rootNode, string stringToFind ) {
    var stack = new Stack<Node>( new[] { rootNode } );
    while( stack.Any() ) {
        var n = stack.Pop();
        if( n.Content == stringToFind ) return n;
        foreach( var child in n.Children ) stack.Push( child );
    }
    return null;
}
+3

linq , , . , , .

public Node FindNode(Node rootNode)
{
    if (rootNode.Content.Contains(stringToFind))
       return rootNode;

    foreach (Node node in rootNode.Children)
    {
        if (node.Content.Contains(stringToFind))
           return node;
        else
           return FindNode(node);
    }

    return null;
}
+2

PLinq

    private Node Find(Node node, Func<Node, bool> predicate)
    {
        if (predicate(node))
            return node;

        foreach (var n in node.Children.AsParallel())
        {
            var found = Find(n, predicate);
            if (found != default(Node))
                return found;
        }
        return default(Node);
    }

:

     var found = Find(root, (n) => n.Content.Contains("3"));
     if (found != default(Node))
         Console.Write("found '{0}'", found.Name);
     else Console.Write("not found");
+1

LINQ- API: "" "", . , "Act", LINQ.

public IEnumerable<Node> Where(Func<Node, bool> condition);

node, Where, . - , (.. ).

. . true/false Find , true, .

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