license_key_formatting.py

"""You are given a license key represented as a string S which consists only alphanumeric character and dashes.
The string is separated into N+1 groups by N dashes.
Given a number K, we would want to reformat the strings 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 all lowercase letters should be converted to uppercase.
Given a non-empty string S and a number K, format the string according to the rules described above."""


class Solution:
    def licenseKeyFormatting(self, S, K):
        """
        :type S: str
        :type K: int
        :rtype: str
        """
        chars = ''.join(S.split('-')).upper()[::-1]
        return '-'.join([chars[i:i + K] for i in range(0, len(chars), K)])[::-1]


if __name__ == '__main__':
    solution = Solution()
    print(solution.licenseKeyFormatting("5F3Z-2e-9-w", 4))
    print(solution.licenseKeyFormatting("2-5g-3-J", 2))