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482. License Key Formatting

String

Problem - License Key Formatting

Easy

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

Solutions

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class Solution:
    def licenseKeyFormatting(self, s: str, k: int) -> str:
        n = len(s)
        result = []
        count = (n - s.count("-")) % k or k

        for i, char in enumerate(s):
            if char == "-":
                continue
            result.append(char.upper())
            count -= 1

            if count == 0:
                count = k
                if i != n - 1:
                    result.append("-")

        return "".join(result).strip("-")

Submission Stats:

  • Runtime: 11 ms (54.08%)
  • Memory: 21.1 MB (10.19%)