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  1. /* package whatever; // don't place package name! */
  2. import java.util.regex.Matcher;
  3. import java.util.regex.Pattern;
  4.  
  5. /* Name of the class has to be "Main" only if the class is public. */
  6. class RomanToDecimalConverter
  7. {
  8. 	public static void main (String[] args) {
  9. 		printRomanToDecimal("XCIX");
  10.         printRomanToDecimal("MMMCMXCIX");
  11.  
  12.         //error cases
  13.         printRomanToDecimal("IIX");
  14.         printRomanToDecimal("IIXX");
  15.         printRomanToDecimal("ABC");
  16.         printRomanToDecimal("IVX");
  17. 	}
  18.  
  19. 	private static void printRomanToDecimal(String s) {
  20. 		int decimal = romanToDecimal(s);
  21. 		String output = decimal != -1 ? ""+decimal : "Invalid roman numerals";
  22. 		System.out.println(s + ": " + output);
  23. 	}
  24.  
  25. 	public static int romanToDecimal(String s) {
  26.         if (s == null || s.isEmpty() || !s.matches("^(M{0,3})(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})$"))
  27.             return -1;
  28.  
  29.         final Matcher matcher = Pattern.compile("M|CM|D|CD|C|XC|L|XL|X|IX|V|IV|I").matcher(s);
  30.         final int[] decimalValues = {1000,900,500,400,100,90,50,40,10,9,5,4,1};
  31.         final String[] romanNumerals = {"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};
  32.         int result = 0;
  33.  
  34.         while (matcher.find())
  35.             for (int i = 0; i < romanNumerals.length; i++)
  36.                 if (romanNumerals[i].equals(matcher.group(0)))
  37.                     result += decimalValues[i];
  38.  
  39.         return result;
  40.     }
  41. }
Success #stdin #stdout 0.04s 711168KB
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stdin
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Standard input is empty
stdout
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XCIX: 99
MMMCMXCIX: 3999
IIX: Invalid roman numerals
IIXX: Invalid roman numerals
ABC: Invalid roman numerals
IVX: Invalid roman numerals
https://ideone.com/tDNzVu
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
public

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