C#使用前序遍历、中序遍历和后序遍历打印二叉树的方法

public class BinaryTreeNode{ public BinaryTreeNode Left { get; set; } public BinaryTreeNode Right { get; set; } public int Data { get; set; } public BinaryTreeNode(int data) {  this.Data = data; }}public enum TreeTraversal{  PREORDER,  INORDER,  POSTORDER}public void PrintTree(BinaryTreeNode root, TreeTraversal treeTraversal){  Action<int> printValue = delegate(int v)  {   Console.Write(v + " ");  };  switch (treeTraversal)  {   case TreeTraversal.PREORDER:    PreOrderTraversal(printValue, root);    break;   case TreeTraversal.INORDER:    InOrderTraversal(printValue, root);    break;   case TreeTraversal.POSTORDER:    PostOrderTraversal(printValue, root);    break;   default: break;  }}public void PreOrderTraversal(Action<int> action, BinaryTreeNode root){  if (root == null)   return;  action(root.Data);  PreOrderTraversal(action, root.Left);  PreOrderTraversal(action, root.Right);}public void InOrderTraversal(Action<int> action, BinaryTreeNode root){  if (root == null)   return;  InOrderTraversal(action, root.Left);  action(root.Data);  InOrderTraversal(action, root.Right);}public void PostOrderTraversal(Action<int> action, BinaryTreeNode root){  if (root == null)   return;  PostOrderTraversal(action, root.Left);  PostOrderTraversal(action, root.Right);  action(root.Data);}