public class Solution
extends Object
482 - License Key Formatting\.
Easy
You are given a license key represented as a string `s` that consists of only alphanumeric characters and dashes. The string is separated into `n + 1` groups by `n` dashes. You are also given an integer `k`.
We want to reformat the string `s` such that each group contains exactly `k` characters, except for the first group, which could be shorter than `k` but still must contain at least one character. Furthermore, there must be a dash inserted between two groups, and you should convert all lowercase letters to uppercase.
Return _the reformatted license key_.
**Example 1:**
**Input:** s = "5F3Z-2e-9-w", k = 4
**Output:** "5F3Z-2E9W"
**Explanation:** The string s has been split into two parts, each part has 4 characters. Note that the two extra dashes are not needed and can be removed.
**Example 2:**
**Input:** s = "2-5g-3-J", k = 2
**Output:** "2-5G-3J"
**Explanation:** The string s has been split into three parts, each part has 2 characters except the first part as it could be shorter as mentioned above.
**Constraints:**
* 1 <= s.length <= 105
* `s` consists of English letters, digits, and dashes `'-'`.
* 1 <= k <= 104