static void Main(string[] args)
{
Treenode n1 = new Treenode();
List <Treenode> l1 = new List <Treenode>();
l1.Add(n1); // create the base case of 1 node
List <List <Treenode> > l = new List <List <Treenode> >(); //initialize the List of List of trees
l.Add(null); // add the base case of 0 node
l.Add(l1); // add the base case of 1 node
//Let user input the number of input numbers of nodes
Console.WriteLine("Please type the number of nodes:");
String k = Console.ReadLine();
int number = Convert.ToInt32(k);
List <Treenode> listtree = new List <Treenode>();
listtree = CreateTree(number, l);
for (int i = 0; i <= listtree.Count - 1; i++) // print all the trees in the list
{
printtree(listtree[i]);
Console.Write("\n");
}
Console.WriteLine("Press Enter to Exit.");
Console.ReadLine();
}
public static List <Treenode> CreateTree(int n, List <List <Treenode> > trees)
{
if (trees.Count > n)
{
return(trees[n]);
}
else
{
List <Treenode> current = new List <Treenode>();
for (int i = n - 1; i >= 0; i--)
{
Treenode node;
int leftnodes = i;
int rightnodes = n - 1 - i;
List <Treenode> lefttrees = CreateTree(leftnodes, trees);
List <Treenode> righttrees = CreateTree(rightnodes, trees);
if (rightnodes > 0 && leftnodes > 0) //When the left tree and the right tree of current node are not null.
{
foreach (Treenode leftnode in lefttrees)
{
node = new Treenode();
node.left = leftnode;
foreach (Treenode rightnode in righttrees)
{
node.right = rightnode;
current.Add(node);
}
}
}
else if (rightnodes > 0 && leftnodes <= 0) //When the left tree of current node is null.
{
foreach (Treenode rightnode in righttrees)
{
node = new Treenode();
node.right = rightnode;
current.Add(node);
}
}
else if (leftnodes > 0 && rightnodes <= 0) //When the right tree of current node is null.
{
foreach (Treenode leftnode in lefttrees)
{
node = new Treenode();
node.left = leftnode;
current.Add(node);
}
}
}
trees.Insert(n, current);
return((List <Treenode>)current);
}
}
public static void printtree(Treenode n)
{
Console.Write("(");
if (n.left != null)
{
printtree(n.left);
}
Console.Write(".");
if (n.right != null)
{
printtree(n.right);
}
Console.Write(")");
}