inorder tree using stack

Author: jackzhenguo

Tree/Tree.TreeLib/InorderStack.cs

@@ -0,0 +1,68 @@
+/* ==============================================================================
+ * 功能描述：InorderStack  
+ * 创 建 者：gz
+ * 创建日期：2017/5/12 15:06:49
+ * ==============================================================================*/
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Windows.Forms;
+using System.Windows.Forms.VisualStyles;
+
+//Given a binary tree, return the inorder traversal of its nodes' values.
+
+//For example:
+//Given binary tree [1,null,2,3],
+//   1
+//    \
+//     2
+//    /
+//   3
+//return [1,3,2].
+
+//Note: Recursive solution is trivial, could you do it iteratively?
+namespace InorderTreeStackSln
+{
+
+    //Definition for a binary tree node.
+    public class TreeNode
+    {
+        public int val;
+        public TreeNode left;
+        public TreeNode right;
+        public TreeNode(int x) { val = x; }
+    }
+
+    /// <summary>
+    /// InorderStack
+    /// </summary>
+    public class InorderStack
+    {
+        public IList<int> InorderTraversal(TreeNode root)
+        {
+            IList<int> rtn = new List<int>();
+            Stack<TreeNode> s = new Stack<TreeNode>();
+            if (root == null) return rtn;
+            s.Push(root);                 
+            while (s.Count>0)
+            {     
+                var tmp = s.Peek();  //tmp可能为null ，因为curNode.right可能为null         
+                while (tmp != null) //tmp=null退出循环
+                {
+                    s.Push(tmp.left);
+                    tmp = tmp.left;
+                }
+                s.Pop(); 
+                if (s.Count == 0) 
+                    return rtn;
+                rtn.Add(s.Peek().val); //访问节点
+                TreeNode curNode = s.Pop();
+                s.Push(curNode.right);
+            }
+            return rtn;
+        }
+    }
+
+
+}