Update 0098.验证二叉搜索树.md

补充:**递归** - 避免初始化最小值做法
This commit is contained in:
ZerenZhang2022
2022-12-27 00:30:43 -05:00
committed by GitHub
parent d2aa61459b
commit b825b5a7c8

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@ -392,7 +392,26 @@ class Solution:
return is_left_valid and is_right_valid
return __isValidBST(root)
```
**递归** - 避免初始化最小值做法:
```python
class Solution:
def isValidBST(self, root: TreeNode) -> bool:
# 规律: BST的中序遍历节点数值是从小到大.
pre = None
def __isValidBST(root: TreeNode) -> bool:
nonlocal pre
if not root:
return True
is_left_valid = __isValidBST(root.left)
if pre and pre.val>=root.val: return False
pre = root
is_right_valid = __isValidBST(root.right)
return is_left_valid and is_right_valid
return __isValidBST(root)
```
```python
迭代-中序遍历
class Solution: