Update 0098.验证二叉搜索树.md

problems/0098.验证二叉搜索树.md

@@ -639,6 +639,29 @@ object Solution {
 }
 ```
 
+## rust
+
+递归：
+
+```rust
+impl Solution {
+    pub fn is_valid_bst(root: Option<Rc<RefCell<TreeNode>>>) -> bool {
+        Self::valid_bst(i64::MIN, i64::MAX, root)
+    }
+    pub fn valid_bst(low: i64, upper: i64, root: Option<Rc<RefCell<TreeNode>>>) -> bool {
+        if root.is_none() {
+            return true;
+        }
+        let root = root.as_ref().unwrap().borrow();
+        if root.val as i64 <= low || root.val as i64 >= upper {
+            return false;
+        }
+        Self::valid_bst(low, root.val as i64, root.left.clone())
+            && Self::valid_bst(root.val as i64, upper, root.right.clone())
+    }
+}
+```
+
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>