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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class RomanToDecimalConverter {
  9.     private static double evaluateNextRomanNumeral(String roman, int pos, double rightNumeral) {
  10.         if (pos < 0) return 0;
  11.         char ch = roman.charAt(pos);
  12.         double value = Math.floor(Math.pow(10, "IXCM".indexOf(ch))) + 5 * Math.floor(Math.pow(10, "VLD".indexOf(ch)));
  13.         return value * Math.signum(value + 0.5 - rightNumeral) + evaluateNextRomanNumeral(roman, pos - 1, value);
  14.     }
  15.  
  16.     public static int evaluateRomanNumerals(String s) {
  17.         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})$"))
  18.             return -1;
  19.         return (int) evaluateNextRomanNumeral(s, s.length() - 1, 0);
  20.     }
  21.  
  22.     public static void main (String[] args) {
  23. 	    printRomanToDecimal("XCIX");
  24. 	    printRomanToDecimal("MMMCMXCIX");
  25.  
  26. 	    //common error cases found in other solutions
  27. 	    printRomanToDecimal("IIX");
  28. 	    printRomanToDecimal("IIXX");
  29. 	    printRomanToDecimal("ABC");
  30. 	    printRomanToDecimal("IVX");
  31. 	}
  32.  
  33. 	private static void printRomanToDecimal(String s) {
  34. 	    //change the conversion method accordingly
  35. 	    int decimal = evaluateRomanNumerals(s);
  36. 	    String output = decimal != -1 ? ""+decimal : "Invalid roman numerals";
  37. 	    System.out.println(s + ": " + output);
  38. 	}
  39. }
Success #stdin #stdout 0.05s 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/Gq6GhY
language:
Java (HotSpot 12)
created:
7 years ago
visibility:
public

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