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 -
sconsists of English letters, digits, and dashes'-'. -
1 <= k <= 104
SOLUTION:
class Solution:
def licenseKeyFormatting(self, s: str, k: int) -> str:
op = []
n = len(s)
i = 0
for c in range(n - 1, -1, -1):
if s[c] != "-":
i += 1
op.append(s[c].upper())
if i % k == 0:
op.append("-")
if len(op) > 0 and op[-1] == "-":
op.pop()
op.reverse()
return "".join(op)
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