剑指offer系列-28 对称的二叉树

class Solution {
public:
    bool isSymmetric(TreeNode* root) {
        if(root==nullptr) return true;
        return Symmetric(root->left,root->right);
    }
    bool Symmetric(TreeNode* left,TreeNode* right){
        if(left==nullptr && right==nullptr) 
            return true;
        if(left==nullptr || right==nullptr) 
            return false;
        return (left->val==right->val) && Symmetric(left->left,right->right) && Symmetric(left->right,right->left);
    }
};