二叉树非递归遍历方法(C#)
时间：2010-09-10 来源：Kevin Pan
前段时间写了二叉树的遍历算法，递归方法很简单几行代码就能搞定，但是非递归算法还是有点伤脑细胞。代码如下，可能有问题，希望博友指正，谢谢。
public class TreeNode
{
public TreeNode LChild
{
get;
set;
}
public TreeNode RChild
{
get;
set;
}
public string Data
{
get;
set;
}
//构造一颗简单的二叉树
public static TreeNode CreateTree()
{
TreeNode root = new TreeNode() { Data = "-" };
root.LChild = new TreeNode() { Data = "+" };
root.RChild = new TreeNode() { Data = "/" };
root.LChild.LChild = new TreeNode() { Data = "a" };
root.LChild.RChild = new TreeNode() { Data = "*" };
root.LChild.RChild.LChild = new TreeNode() { Data = "b" };
root.LChild.RChild.RChild = new TreeNode() { Data = "-" };
root.LChild.RChild.RChild.LChild = new TreeNode() { Data = "c" };
root.LChild.RChild.RChild.RChild = new TreeNode() { Data = "d" };
root.RChild.LChild = new TreeNode() { Data = "e" };
root.RChild.RChild = new TreeNode() { Data = "f" };
return root;
}
//递归先序遍历
public static void PreOrderTranverse(TreeNode root)
{
if (root != null)
{
PrintNode(root);
PreOrderTranverse(root.LChild);
PreOrderTranverse(root.RChild);
}
}
//递归中序遍历
public static void InOrderTransverse(TreeNode root)
{
if (root != null)
{
InOrderTransverse(root.LChild);
PrintNode(root);
InOrderTransverse(root.RChild);
}
}
//递归后续遍历
public static void PostOrderTransverse(TreeNode root)
{
if (root != null)
{
PostOrderTransverse(root.LChild);
PostOrderTransverse(root.RChild);
PrintNode(root);
}
}
//非递归中序遍历
public static void NonrecursiveInOrderTraverse(TreeNode root)
{
Stack<TreeNode> nodeStack = new Stack<TreeNode>();
if (root == null)
{
return;
}
var node = root;
while (node != null || nodeStack.Count != 0)
{
while (node != null)
{
nodeStack.Push(node);
node = node.LChild;
}
node = nodeStack.Pop();
PrintNode(node);
node = node.RChild;
}
}
//非递归后续遍历
public static void NonrecursivePostOrderTraverse(TreeNode root)
{
Stack<TreeNode> nodeStack = new Stack<TreeNode>();
if (root == null)
{
return;
}
var node = root;
while (node != null || nodeStack.Count != 0)
{
while (node != null)
{
nodeStack.Push(node);
if (node.LChild == null)
{
node = node.RChild;
}
else
{
node = node.LChild;
}
}
node = nodeStack.Pop();
PrintNode(node);
if (nodeStack.Count != 0 && node == nodeStack.Peek().LChild)
{
node = nodeStack.Peek().RChild;
}
else
{
node = null;
}
}
}
//打印树节点
public static void PrintNode(TreeNode node)
{
System.Console.Write(node.Data);
}
}
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