From 7af58b92b86e045998ce3f7ceca186d73809cbdd Mon Sep 17 00:00:00 2001
From: Steve2020 <841532108@qq.com>
Date: Thu, 17 Feb 2022 15:07:13 +0800
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---
 problems/0098.验证二叉搜索树.md | 42 ++++++++++++++++++++++++++
 1 file changed, 42 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 4ed29619..c0f3e039 100644
--- a/problems/0098.验证二叉搜索树.md
+++ b/problems/0098.验证二叉搜索树.md
@@ -526,6 +526,48 @@ var isValidBST = function (root) {
 };
 ```
 
+## TypeScript
+
+> 辅助数组解决：
+
+```typescript
+function isValidBST(root: TreeNode | null): boolean {
+    const traversalArr: number[] = [];
+    function inorderTraverse(root: TreeNode | null): void {
+        if (root === null) return;
+        inorderTraverse(root.left);
+        traversalArr.push(root.val);
+        inorderTraverse(root.right);
+    }
+    inorderTraverse(root);
+    for (let i = 0, length = traversalArr.length; i < length - 1; i++) {
+        if (traversalArr[i] >= traversalArr[i + 1]) return false;
+    }
+    return true;
+};
+```
+
+> 递归中解决：
+
+```typescript
+function isValidBST(root: TreeNode | null): boolean {
+    let maxVal = -Infinity;
+    function inorderTraverse(root: TreeNode | null): boolean {
+        if (root === null) return true;
+        let leftValid: boolean = inorderTraverse(root.left);
+        if (!leftValid) return false;
+        if (maxVal < root.val) {
+            maxVal = root.val
+        } else {
+            return false;
+        }
+        let rightValid: boolean = inorderTraverse(root.right);
+        return leftValid && rightValid;
+    }
+    return inorderTraverse(root);
+};
+```
+
 
 
 -----------------------