【LeetCode】 101. 对称二叉树

题目

题解

看了leetcode官方才想出来，实在是短路，递归是在是整不出来。。

https://leetcode-cn.com/problems/symmetric-tree/solution/dui-cheng-er-cha-shu-by-leetcode/

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public boolean isSymmetric(TreeNode root) {
        return isMirror(root, root);
    }

    public static boolean isMirror(TreeNode node1, TreeNode node2) {
        if (node1 == null && node2 == null) return true;
        if (node1 == null || node2 == null) return false;
        return (node1.val == node2.val) && isMirror(node1.right, node2.left) && isMirror(node1.left, node2.right);
    }
}