""" License Key Formatting - 
    https://leetcode.com/problems/license-key-formatting/description/

    Now you are given a string S, which represents a software license key 
    which we would like to format. The string S is composed of alphanumerical 
    characters and dashes. The dashes split the alphanumerical characters within 
    the string into groups. (i.e. if there are M dashes, the string is split 
    into M+1 groups). The dashes in the given string are possibly misplaced.

    We want each group of characters to be of length K (except for possibly 
    the first group, which could be shorter, but still must contain at least 
    one character). To satisfy this requirement, we will reinsert dashes. 
    Additionally, all the lower case letters in the string must be converted 
    to upper case.

    So, you are given a non-empty string S, representing a license key to 
    format, and an integer K. And you need to return the license key 
    formatted according to the description above.

    Example 1:
    Input: S = "2-4A0r7-4k", K = 4

    Output: "24A0-R74K"

    Explanation: The string S has been split into two parts, each part has 4 characters.
    
    Example 2:
    Input: S = "2-4A0r7-4k", K = 3

    Output: "24-A0R-74K"

    Explanation: The string S has been split into three parts, each part has 3 characters except the first part as it could be shorter as said above.
    
    Note:
    The length of string S will not exceed 12,000, and K is a positive integer.
    String S consists only of alphanumerical characters (a-z and/or A-Z and/or 0-9) and dashes(-).
    String S is non-empty.
"""

class Solution(object):
    def licenseKeyFormatting(self, S, K):
        """
        :type S: str
        :type K: int
        :rtype: str
        """
        def replace_dashes(S):
            n = []
            for i in range(len(S)):
                if S[i] != '-':
                    n.append(S[i])
            return n

        S = S.upper()
        S = replace_dashes(S)
        #print(S)
        new = []
        i = len(S)-1
        while i >= K:
            for j in range(K):
                new.append(S[i])
                i -= 1
            if i >= 0:
                new.append('-')

        while i >= 0:
            new.append(S[i])
            i -= 1
        return "".join(new[::-1])


# a = Solution()
# print(a.licenseKeyFormatting("a-a-a-a-", 1))