From dc03975acdb47f6c5eaa0b2b3a47d119f8fe78f2 Mon Sep 17 00:00:00 2001
From: NevS <1173325467@qq.com>
Date: Tue, 29 Jun 2021 00:20:13 +0800
Subject: [PATCH] =?UTF-8?q?=E5=A2=9E=E5=8A=A0=200098.=E9=AA=8C=E8=AF=81?=
 =?UTF-8?q?=E4=BA=8C=E5=8F=89=E6=90=9C=E7=B4=A2=E6=A0=91=20go=E7=89=88=20?=
 =?UTF-8?q?=EF=BC=88=E5=A2=9E=E5=8A=A0=E4=B8=AD=E5=BA=8F=E9=81=8D=E5=8E=86?=
 =?UTF-8?q?=E8=A7=A3=E9=A2=98=E6=B3=95=EF=BC=89?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

增加中序遍历解题法
---
 problems/0098.验证二叉搜索树.md | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/problems/0098.验证二叉搜索树.md b/problems/0098.验证二叉搜索树.md
index e38c5ade..b93d8cd5 100644
--- a/problems/0098.验证二叉搜索树.md
+++ b/problems/0098.验证二叉搜索树.md
@@ -376,6 +376,28 @@ func isBST(root *TreeNode, min, max int) bool {
 	return isBST(root.Left, min, root.Val) && isBST(root.Right, root.Val, max)
 }
 ```
+```go
+// 中序遍历解法
+func isValidBST(root *TreeNode) bool {
+    // 保存上一个指针
+    var prev *TreeNode
+    var travel func(node *TreeNode) bool
+    travel = func(node *TreeNode) bool {
+        if node == nil {
+            return true
+        }
+        leftRes := travel(node.Left)
+        // 当前值小于等于前一个节点的值，返回false
+        if prev != nil && node.Val <= prev.Val {
+            return false
+        }
+        prev = node
+        rightRes := travel(node.Right)
+        return leftRes && rightRes
+    }
+    return travel(root)
+}
+```
 
 JavaScript版本