leetcode刷题思路总结_对称的二叉树

class Solution {
public:
    bool isSymmetric(TreeNode* root) {
        if(!root) return true;                     
        return dfs(root->left,root->right);
    }
   
    bool dfs(TreeNode* t1,TreeNode* t2)  
    {
    if(!t1||!t2) return !t1&&!t2;                                //只有两个节点同时为空 返回true
       if(t1->val!=t2->val) return false;
      return dfs(t1->left,t2->right)&&dfs(t1->right,t2->left);      
    }
}