License Key Formatting Python Solution

lcpy gen -n 482   # by problem number
lcpy gen -s license_key_formatting   # by problem name

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.

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.

class Solution:
    # Time: O(n)
    # Space: O(n)
    def license_key_formatting(self, s: str, k: int) -> str:
        chars = s.replace("-", "").upper()
        first = len(chars) % k or k
        groups = [chars[:first]] if chars else []
        groups.extend(chars[i : i + k] for i in range(first, len(chars), k))
        return "-".join(groups)