public class Solution
extends Object
1399 - Count Largest Group\.
Easy
You are given an integer `n`.
Each number from `1` to `n` is grouped according to the sum of its digits.
Return _the number of groups that have the largest size_.
**Example 1:**
**Input:** n = 13
**Output:** 4
**Explanation:** There are 9 groups in total, they are grouped according sum of its digits of numbers from 1 to 13:
[1,10], [2,11], [3,12], [4,13], [5], [6], [7], [8], [9].
There are 4 groups with largest size.
**Example 2:**
**Input:** n = 2
**Output:** 2
**Explanation:** There are 2 groups [1], [2] of size 1.
**Constraints:**
* 1 <= n <= 104