对称的二叉树

/*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 judge(pRoot,pRoot);    }    bool judge(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;        return judge(root1->left,root2->right)&&judge(root1->right,root2->left);    }};