解题思路

递归来做

code

 public TreeNode mergeTrees(TreeNode t1, TreeNode t2) {
        if(t1==null)
            return t2;
        if(t2==null)
            return t1;
        TreeNode res = new TreeNode(t1.val+t2.val);
        res.left = mergeTrees(t1.left,t2.left);
        res.right = mergeTrees(t1.right,t2.right);
        return res;
    }

key

二叉树 递归