力扣刷题——101. 对称二叉树

101. 对称二叉树给你一个二叉树的根节点 root 检查它是否轴对称。示例 1输入root [1,2,2,3,4,4,3]输出true示例 2输入root [1,2,2,null,3,null,3]输出false提示树中节点数目在范围 [1, 1000] 内-100 Node.val 100实现代码Python:# Definition for a binary tree node.# class TreeNode:# def __init__(self, val0, leftNone, rightNone):# self.val val# self.left left# self.right rightclassSolution:defisSymmetric(self,root:Optional[TreeNode])-bool:ifnotroot:returnTruedefcampare(left,right):ifleftandnotright:returnFalseelifnotleftandright:returnFalseelifnotleftandnotright:returnTrueelifleft.val!right.val:returnFalseoutsidecampare(left.left,right.right)insidecampare(left.right,right.left)returnoutsideandinsidereturncampare(root.left,root.right)分析本题判断对称二叉树其实就是判断递归两棵二叉树是否对称递归的顺序为后根遍历不能使用前、中序遍历