From 372b92bf7cd5bbbb00c96717806bed7f254da655 Mon Sep 17 00:00:00 2001
From: dekunma <53892579+dekunma@users.noreply.github.com>
Date: Wed, 11 Nov 2020 14:21:23 +0800
Subject: [PATCH] =?UTF-8?q?=E3=80=9098.=20=E9=AA=8C=E8=AF=81=E4=BA=8C?=
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---
 .../二叉搜索树操作集锦.md            | 34 ++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/数据结构系列/二叉搜索树操作集锦.md b/数据结构系列/二叉搜索树操作集锦.md
index 801b8fb..b30ceeb 100644
--- a/数据结构系列/二叉搜索树操作集锦.md
+++ b/数据结构系列/二叉搜索树操作集锦.md
@@ -310,4 +310,36 @@ void BST(TreeNode root, int target) {
 <img src="../pictures/qrcode.jpg" width=200 >
 </p>
 
-======其他语言代码======
\ No newline at end of file
+======其他语言代码======  
+[dekunma](https://www.linkedin.com/in/dekun-ma-036a9b198/)提供第98题C++代码：  
+```C++
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    bool isValidBST(TreeNode* root) {
+        // 用helper method求解
+        return isValidBST(root, nullptr, nullptr);
+    }
+
+    bool isValidBST(TreeNode* root, TreeNode* min, TreeNode* max) {
+        // base case, root为nullptr
+        if (!root) return true;
+
+        // 不符合BST的条件
+        if (min && root->val <= min->val) return false;
+        if (max && root->val >= max->val) return false;
+
+        // 向左右子树分别递归求解
+        return isValidBST(root->left, min, root) 
+            && isValidBST(root->right, root, max);
+    }
+};
+```