May 14, 2023 · Apr 25, 2023 · Apr 25, 2023 · Apr 27, 2023 · May 14, 2023 · May 14, 2023
diff --git a/problems/0098.验证二叉搜索树.md b/problems/0098.验证二叉搜索树.md
Original file line number	Diff line number	Diff line change
Expand Up		@@ -259,6 +259,36 @@ public:

		## Java

	```Java
	//使用統一迭代法
	class Solution {
	public boolean isValidBST(TreeNode root) {
	Stack<TreeNode> stack = new Stack<>();
	TreeNode pre = null;
	if(root != null)
	stack.add(root);
	while(!stack.isEmpty()){
	TreeNode curr = stack.peek();
	if(curr != null){
	stack.pop();
	if(curr.right != null)
	stack.add(curr.right);
	stack.add(curr);
	stack.add(null);
	if(curr.left != null)
	stack.add(curr.left);
	}else{
	stack.pop();
	TreeNode temp = stack.pop();
	if(pre != null && pre.val >= temp.val)
	return false;
	pre = temp;
	}
	}
	return true;
	}
	}
	```
		```Java
		class Solution {
		// 递归
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