Leetcode 101 Symmetric Tree 二叉树

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12 
13     bool isSymmetric(TreeNode* root) {
14         if(!root) return true;
15         return isSameTree(root->left, root->right);
16         
17     }
18     bool isSameTree(TreeNode* p, TreeNode* q) {
19         if(!p && !q) {
20             return true;
21         }
22         else if(!p||!q){
23             return false;
24         }
25         else{
26             if(p->val != q->val ) return false;
27             else return isSameTree(p->left, q->right) && isSameTree(p->right, q->left);
28         }
29     }
30 };