1、前言

2、思路

这道题的思路可以拿对称二叉树的解法来做，只不过相同的树比较的是 left.left 跟 right.left，和 left.right 跟 right.right。

3、代码

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if(p == null && q == null){
            return true;
        }

        if(p == null || q == null){
            return false;
        }

        return p.val == q.val && isSameTree(p.left, q.left)
            && isSameTree(p.right, q.right);
    }
}