leetcode/romanToInt.php

<?php

class Solution {
    const romanToIntMap = [
        'M' => 1000,
        'D' => 500,
        'C' => 100,
        'L' => 50,
        'X' => 10,
        'V' => 5,
        'I' => 1,
    ];

    /**
     * @param mixed $str
     * @static
     * @access public
     * @return int
     */
    public static function romanToInt(string $str, $checkInvalid = false): int
    {
        if ($checkInvalid && !self::isRomanValid($str)) {
            throw new RuntimeException('Given number is invalid');
        }

        $total = 0;

        $letters = str_split(strtoupper($str));

        for ($i = 0; $i < count($letters); $i++) {
            $letterVal = self::romanToIntMap[$letters[$i]];
            $nextLetterVal = isset($letters[$i + 1]) ? self::romanToIntMap[$letters[$i + 1]] : 0;

            if ($letterVal < $nextLetterVal) {
                $total -= $letterVal;
                continue;
            }

            $total += $letterVal;
        }

        return $total;
    }

    /**
     * @param string $str
     * @static
     * @access public
     * @return bool
     */
    public static function isRomanValid(string $str): bool
    {
        // If an empty string is provided, return false,
        // as the romans did not have a concept of 0
        // (btw, they called it "nulla")
        if ($str === '') {
            return false;
        }

        $letters = str_split(strtoupper($str));

        $currentLetter = $letters[0];
        $count = 0;

        for ($i = 1; $i < count($letters); $i++) {

            // Ensure V, L, and D are not repeated, and
            // if I, X, and C are the only subtractive operators
            $letterVal = self::romanToIntMap[$currentLetter];
            $nextLetterVal = isset($letters[$i]) ? self::romanToIntMap[$letters[$i]] : 0;
            $currentVal = substr($letterVal, 0, 1);
            if ($letterVal <= $nextLetterVal && ($currentVal === '5' || $nextLetterVal === '1000')) {
                return false;
            }

            // Check if a number is repeated more than 3 times
            $letterSameAsNext = $currentLetter === $letters[$i];
            $count = $letterSameAsNext ? $count + 1 : 0;
            if ($count >= 3) {
                return false;
            }


            $currentLetter = $letters[$i] ?? '';
        }

        return true;
    }

    /**
     * @param mixed $str
     * @param mixed $expectedVal
     * @static
     * @access public
     * @return void
     */
    public static function testRomanToInt(string $str, int $expectedVal): void
    {
        $val = self::romanToInt($str);
        if ($val != $expectedVal) {
            echo sprintf(
                'Failed: The value of \'%d\' did not match the expected value of \'%d\' for \'%s\'' . PHP_EOL,
                $val,
                $expectedVal,
                $str
            );
            return;
        }

        echo sprintf(
            'Succeeded: The value of \'%d\' matched the expected value of \'%s\'' . PHP_EOL,
            $val,
            $str
        );
    }

    /**
     * @param string $str
     * @param bool $expectedValid
     * @static
     * @access public
     * @return void
     */
    public static function testIsRomanValid(string $str, bool $expectedValid) {
        $val = self::isRomanValid($str);
        if ($val != $expectedValid) {
            echo sprintf(
                'Failed: The value of \'%s\' did not match the expected value of \'%s\' for \'%s\'' . PHP_EOL,
                $val ? 'True' : 'False',
                $expectedValid ? 'True' : 'False',
                $str
            );
            return;
        }

        echo sprintf(
            'Succeeded: The value of \'%s\' matched the expected value of \'%s\'' . PHP_EOL,
            $val ? 'True' : 'False',
            $str
        );

    }
}

// Tests
Solution::testRomanToInt('I', 1);
Solution::testRomanToInt('III', 3);
Solution::testRomanToInt('IV', 4);
Solution::testRomanToInt('V', 5);
Solution::testRomanToInt('VI', 6);
Solution::testRomanToInt('IX', 9);
Solution::testRomanToInt('X', 10);
Solution::testRomanToInt('XI', 11);
Solution::testRomanToInt('LVIII', 58);
Solution::testRomanToInt('MCMXCIV', 1994);

// Validity tests
Solution::testIsRomanValid('III', true);
Solution::testIsRomanValid('IIII', false);
Solution::testIsRomanValid('VI', true);
Solution::testIsRomanValid('VV', false);
Solution::testIsRomanValid('LL', false);
Solution::testIsRomanValid('VL', false);
Solution::testIsRomanValid('DD', false);
Solution::testIsRomanValid('MCMXCIV', true);