license-key-formatting.js

/**
482. License Key Formatting

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
*/

/**
 * @param {string} s
 * @param {number} k
 * @return {string}
 */
var licenseKeyFormatting = function (s, k) {
  const normalized = s
    .split("-")
    .join("")
    .split("")
    .map((char) => char.toUpperCase());
  const length = normalized.length;
  const lengthFirstPart = length % k;
  const parts = [];

  if (lengthFirstPart > 0) {
    parts.push(normalized.slice(0, lengthFirstPart).join(""));
  }

  let index = lengthFirstPart;

  while (index < length) {
    parts.push(normalized.slice(index, index + k).join(""));

    index += k;
  }

  const result = parts.join("-");

  return result;
};