剑指offer——对称的二叉树

#include <iostream>
using namespace std; 

struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};

class Solution {
    public:
        bool isSymmetrical(TreeNode* pRoot){
            return this->IsSymmetrical(pRoot,pRoot);        
        }

        bool IsSymmetrical(TreeNode* root1,TreeNode* root2){
            if(root1 == NULL && root2 == NULL){
                return true;
            }
            if(root1 == NULL || root2 == NULL){
                return false;
            }
            if(root1->val != root2->val){
                return false;
            }else{
                return this->IsSymmetrical(root1->left,root2->right)&& this->IsSymmetrical(root1->right,root2->left);
            }
        }
};