Merge pull request #1785 from fwqaaq/patch-5

Update 0098.验证二叉搜索树.md about rust

problems/0098.验证二叉搜索树.md

@@ -637,6 +637,55 @@ 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())
+    }
+}
+```
+
+辅助数组：
+
+```rust
+impl Solution {
+    pub fn is_valid_bst(root: Option<Rc<RefCell<TreeNode>>>) -> bool {
+        let mut vec = vec![];
+        Self::valid_bst(root, &mut vec);
+        for i in 1..vec.len() {
+            if vec[i] <= vec[i - 1] {
+                return false;
+            }
+        }
+        true
+    }
+    pub fn valid_bst(root: Option<Rc<RefCell<TreeNode>>>, mut v: &mut Vec<i64>) {
+        if root.is_none() {
+            return;
+        }
+        let node = root.as_ref().unwrap().borrow();
+        Self::valid_bst(node.left.clone(), v);
+        v.push(node.val as i64);
+        Self::valid_bst(node.right.clone(), v);
+    }
+}
+```
+
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