101 Symmetric tree

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    
    bool test(TreeNode* p,TreeNode* q)
    {
        
        //both side empty
        if(p==NULL and q==NULL) return true;
        //anyone side empty
        else if(p==NULL or q==NULL) return false;
        //value check left and right
        else if(p->val!=q->val)
            return false;
        
        
        return test(p->left ,q->right) and test(p->right,q->left);
        
    }
    
    
    bool isSymmetric(TreeNode* root) {
        
    if(root==NULL) return true;
        
       
        
    return test(root->left,root->right);
        
        
        
        
    }
};