From 5d9d37f01d59b2fa95001018fb24e4b74e2a04f9 Mon Sep 17 00:00:00 2001
From: eeee0717 <70054568+eeee0717@users.noreply.github.com>
Date: Sun, 12 Nov 2023 09:15:59 +0800
Subject: [PATCH] =?UTF-8?q?Update.=E4=BA=8C=E5=8F=89=E6=A0=91=E8=BF=AD?=
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---
 problems/二叉树的迭代遍历.md | 61 ++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/problems/二叉树的迭代遍历.md b/problems/二叉树的迭代遍历.md
index 69007995..e39709b8 100644
--- a/problems/二叉树的迭代遍历.md
+++ b/problems/二叉树的迭代遍历.md
@@ -695,6 +695,67 @@ impl Solution {
     }
 }
 ```
+### C#
+```C#
+// 前序遍历
+public IList<int> PreorderTraversal(TreeNode root)
+{
+    var st = new Stack<TreeNode>();
+    var res = new List<int>();
+    if (root == null) return res;
+    st.Push(root);
+    while (st.Count != 0)
+    {
+        var node = st.Pop();
+        res.Add(node.val);
+        if (node.right != null)
+            st.Push(node.right);
+        if (node.left != null)
+            st.Push(node.left);
+    }
+    return res;
+}  
+
+// 中序遍历
+public IList<int> InorderTraversal(TreeNode root)
+{
+    var st = new Stack<TreeNode>();
+    var res = new List<int>();
+    var cur = root;
+    while (st.Count != 0 || cur != null)
+    {
+        if (cur != null)
+        {
+            st.Push(cur);
+            cur = cur.left;
+        }
+        else
+        {
+            cur = st.Pop();
+            res.Add(cur.val);
+            cur = cur.right;
+        }
+    }
+    return res;
+}
+// 后序遍历
+public IList<int> PostorderTraversal(TreeNode root)
+{
+    var res = new List<int>();
+    var st = new Stack<TreeNode>();
+    if (root == null) return res;
+    st.Push(root);
+    while (st.Count != 0)
+    {
+        var cur = st.Pop();
+        res.Add(cur.val);
+        if (cur.left != null) st.Push(cur.left);
+        if (cur.right != null) st.Push(cur.right);
+    }
+    res.Reverse(0, res.Count());
+    return res;
+}
+```
 
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