public boolean isContains (TreeNode root1, TreeNode root2) {
        // write code here
        if(root1 == null ) return false;
        if(root2 == null) return true;

        return isContains(root1.left , root2) || isContains(root1.right, root2) 
            || isSame(root1,root2);
    }

    /* 判断两棵树是否完全相等 */
    public boolean isSame(TreeNode p, TreeNode q){
        if(p == null && q == null) return true;
        if(p == null || q == null || p.val != q.val) return false;

        return isSame(p.left, q.left) && isSame(p.right , q. right);
    }