<?php
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class Solution {
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const romanToIntMap = [
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'M' => 1000,
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'D' => 500,
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'C' => 100,
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'L' => 50,
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'X' => 10,
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'V' => 5,
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'I' => 1,
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];
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/**
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* @param mixed $str
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* @static
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* @access public
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* @return int
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*/
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public static function romanToInt(string $str, $checkInvalid = false): int
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{
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if ($checkInvalid && !self::isRomanValid($str)) {
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throw new RuntimeException('Given number is invalid');
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}
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$total = 0;
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$letters = str_split(strtoupper($str));
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for ($i = 0; $i < count($letters); $i++) {
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$letterVal = self::romanToIntMap[$letters[$i]];
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$nextLetterVal = isset($letters[$i + 1]) ? self::romanToIntMap[$letters[$i + 1]] : 0;
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if ($letterVal < $nextLetterVal) {
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$total -= $letterVal;
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continue;
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}
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$total += $letterVal;
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}
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return $total;
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}
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/**
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* @param string $str
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* @static
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* @access public
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* @return bool
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*/
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public static function isRomanValid(string $str): bool
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{
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// If an empty string is provided, return false,
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// as the romans did not have a concept of 0
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// (btw, they called it "nulla")
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if ($str === '') {
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return false;
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}
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$letters = str_split(strtoupper($str));
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$currentLetter = $letters[0];
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$count = 0;
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for ($i = 1; $i < count($letters); $i++) {
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// Ensure V, L, and D are not repeated, and
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// if I, X, and C are the only subtractive operators
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$letterVal = self::romanToIntMap[$currentLetter];
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$nextLetterVal = isset($letters[$i]) ? self::romanToIntMap[$letters[$i]] : 0;
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$currentVal = substr($letterVal, 0, 1);
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if ($letterVal <= $nextLetterVal && ($currentVal === '5' || $nextLetterVal === '1000')) {
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return false;
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}
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// Check if a number is repeated more than 3 times
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$letterSameAsNext = $currentLetter === $letters[$i];
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$count = $letterSameAsNext ? $count + 1 : 0;
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if ($count >= 3) {
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return false;
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}
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$currentLetter = $letters[$i] ?? '';
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}
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return true;
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}
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/**
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* @param mixed $str
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* @param mixed $expectedVal
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* @static
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* @access public
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* @return void
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*/
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public static function testRomanToInt(string $str, int $expectedVal): void
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{
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$val = self::romanToInt($str);
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if ($val != $expectedVal) {
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echo sprintf(
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'Failed: The value of \'%d\' did not match the expected value of \'%d\' for \'%s\'' . PHP_EOL,
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$val,
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$expectedVal,
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$str
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);
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return;
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}
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echo sprintf(
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'Succeeded: The value of \'%d\' matched the expected value of \'%s\'' . PHP_EOL,
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$val,
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$str
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);
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}
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/**
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* @param string $str
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* @param bool $expectedValid
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* @static
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* @access public
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* @return void
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*/
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public static function testIsRomanValid(string $str, bool $expectedValid) {
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$val = self::isRomanValid($str);
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if ($val != $expectedValid) {
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echo sprintf(
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'Failed: The value of \'%s\' did not match the expected value of \'%s\' for \'%s\'' . PHP_EOL,
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$val ? 'True' : 'False',
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$expectedValid ? 'True' : 'False',
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$str
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);
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return;
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}
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echo sprintf(
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'Succeeded: The value of \'%d\' matched the expected value of \'%s\'' . PHP_EOL,
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$val ? 'True' : 'False',
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$str
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);
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}
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}
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// Tests
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Solution::testRomanToInt('I', 1);
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Solution::testRomanToInt('III', 3);
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Solution::testRomanToInt('IV', 4);
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Solution::testRomanToInt('V', 5);
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Solution::testRomanToInt('VI', 6);
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Solution::testRomanToInt('IX', 9);
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Solution::testRomanToInt('X', 10);
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Solution::testRomanToInt('XI', 11);
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Solution::testRomanToInt('LVIII', 58);
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Solution::testRomanToInt('MCMXCIV', 1994);
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// Validity tests
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Solution::testIsRomanValid('III', true);
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Solution::testIsRomanValid('IIII', false);
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Solution::testIsRomanValid('VI', true);
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Solution::testIsRomanValid('VV', false);
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Solution::testIsRomanValid('LL', false);
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Solution::testIsRomanValid('VL', false);
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Solution::testIsRomanValid('DD', false);
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Solution::testIsRomanValid('MCMXCIV', true);
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