class Solution:
def licenseKeyFormatting(self, S, K):
"""
:type S: str
:type K: int
:rtype: str
"""
"""
Input: S = "2-5g-3-J", K = 2
Output: "2-5G-3J"
一些指令:
str.upper()
str.lower()
str.isalnum()
str.replace()
str.join([iterable])
"""
S = S.replace("-", "").upper()[::-1]
return '-'.join(S[i:i+K] for i in range(0, len(S), K))[::-1]
