Question

I have a Node structure as below,this Node has stringdata and list of nodes as it’s children. I wanted to search a data in this tree
I wrote a recursive function FindNode(Node intree,string target)

public class Node
{
   public string Data;
   public List<Node> Children = new List<Node>();
   //some code
   public Node(string r)
   {
        this.Data = r;
   }

   public string getData()
   {
          return this.Data;
   }

   //some code
   public List<Node> getchildren()
   {
         return this.Children;
    }
       //some code
}

target is the string which I want to find and the intree is the begining of the tree(ROOT)
I have problem after while loop what should I return after that?
If I am wrong how should I write it?

public Node FindNode(Node intree,string target)
{
    if(intree.getData()==target)
          return intree;
    else 
    {
         while(intree.getchildren()!=null) 
         {
             foreach(Node n in intree.getchildren())
              {
                   FindNode(n,target);
              }
         }
     }
}

Answer 1

Use this one:

public Node FindNode(Node intree,string target)
{
    if(intree.getData()==target)
          return intree;
    else 
    {

              foreach(Node n in intree.getchildren())
              {                
                  Node node = FindNode(n,target) ; //CHECK FOR RETURN 

                  if(node != null) 
                      return node;            

              }

     }

     return null;
}

The difference is that I checked for return of FindNode method, and if it’s not null, return result.

Just note that in case of dupplicated nodes in the tree (nodes with the same string) it will return first occuarance.