Leetcode学习笔记：#101. Symmetric Tree

最新推荐文章于 2025-01-20 23:11:39 发布

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最新推荐文章于 2025-01-20 23:11:39 发布

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该博客是Leetcode #101对称二叉树的学习笔记。题目要求判断给定二叉树是否为自身镜像，即围绕中心对称。给出了对称和非对称二叉树的示例，并说明了实现思路是递归判断左节点是否等于右节点。

Leetcode学习笔记：#101. Symmetric Tree

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).

For example, this binary tree [1,2,2,3,4,4,3] is symmetric:

/
2 2
/ \ /
3 4 4 3

But the following [1,2,2,null,3,null,3] is not:

/
2 2
\
3 3

实现：

public boolean isSymmetric(TreeNode root){
	return root == null || isSymmetricHelper(rrot.left, root.right);
}

public boolean isSymmetricHelper(TreeNode left, TreeNode right){
	if(left == null || right == null)
		return left==right;
	if(left.val != right.val)
		return false;
	return isSymmeticHelper(left.left, right.right) && isSymmetricHelper(left.right, right.left);
}

思路：
递归判断左节点是否等于右节点