LicenseKeyFormatting.php

<?php

namespace App;

/**
 * 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.
 *
 * https://leetcode.com/problems/license-key-formatting
 */
class LicenseKeyFormatting
{
    /**
     * @param string $str
     * @param int $k
     * @return string
     */
    public function licenseKeyFormatting(string $str, int $k): string
    {
        $str = strtoupper(str_replace('-', '', $str));
        $remainder = strlen($str) % $k;
        $currentIndex = 0;
        $result = '';
        while ($currentIndex < strlen($str)) {
            if ($currentIndex === 0 && $remainder > 0) {
                $result .= sprintf('%s-', substr($str, $currentIndex, $remainder));
                $currentIndex += $remainder;
            } else {
                $result .= sprintf('%s-', substr($str, $currentIndex, $k));
                $currentIndex += $k;
            }
        }
        return substr($result, 0, -1);
    }
}