AWS同步监控报错 botocore.exceptions.ClientError: An error occurred (AuthFailure) when calling the DescribeInstances operation: AWS was not able to validate the provided access credentials 原因 计算机时间不同步
问题描述: Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node's
题目连接:Leetcode 098 Validate Binary Search Tree 解题思路:每个结点要维护当前子树结点中的最小值,和最大值。然后如果左结点不为空,递归判定左子树,并且左子树中的最大值不能大于当前值。右子树同理,但是最小值不能小于当前值。 /*** Definition for a binary tree node.* struct TreeNode {* in