class Solution {
public:
   bool cmp(TreeNode* A, TreeNode* B)
    {
        if(!B) return true;
        if(!A || A->val != B->val)
        return false;

        return cmp(A->left,B->left) && cmp(A->right,B->right);
    }

    bool isSubStructure(TreeNode* A, TreeNode* B) {
        if(!A || !B)
        return false;

        return cmp(A,B)|| isSubStructure(A->left,B) || isSubStructure(A->right,B);
    }
};