0482-license-key-formatting¶

Description¶

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

Solution(Python)¶

class Solution:
    def licenseKeyFormatting(self, s: str, k: int) -> str:
        total_character_count = sum([1 for c in s if c != '-'])
        first_group_size = total_character_count % k
        if first_group_size == 0:
            first_group_size = k
        ans = []
        i = 0
        count = 0
        n = len(s)
        while i  < n:
            if (count == first_group_size):
                count = 0

                break
            if s[i] != '-':
                count +=1
                ans.append(s[i].upper())
            i+=1
        if i>= n:
            return ''.join(ans)
        ans.append('-')

        while i < n:
            if s[i] != '-':
                if count == k:
                    ans.append('-')
                    count = 0 
                ans.append(s[i].upper())
                count+=1
            i+=1
        return ''.join(ans)



        