RomanNum

import java.io.*;
import java.util.*;
/**
Chase Keskinyan
12/16/19
Mr.Goldman
Period 9 APCSA
 */
public class RomanNumeral
{
  static PrintStream Richard;
  public static String Reverse(int input)
  {
      if (input < 1 || input > 3999)
      {
          return "Invalid Roman Number Value";
      }

      String s = "";
      int[] nums = new int[]{1000,900,500,400,100,90,50,40,10,9,5,4,1};
      String[] roman = new String[]{"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};

      for(int i = 0; input>=1; i++)
      {
          if(input >= nums[i])
          {
              int n = input/nums[i];

              for(int j = 0; j<n; j++)
              {
                  s += roman[i];
              }

              input -= nums[i]*n;
          }
      }

      return s;
   }

  public static int convert(String r)
  {
    int count = 0;
    for(int i = 0; i < r.length() - 1; i++)
    {
        if(getDigitValue(r.charAt(i)) == 0)
        {
            return 0;
        }
        else if(getDigitValue(r.charAt(i)) < getDigitValue(r.charAt(i + 1)))
        {
            count -= getDigitValue(r.charAt(i));
        }
        else
        {
            count += getDigitValue(r.charAt(i));
        }
    }
    count += getDigitValue(r.charAt(r.length() - 1));
    return count;
  }

  public static int getDigitValue(char ch)
  {
      if(ch == 'I')
      {
          return 1;
      }

      else if(ch == 'V')
      {
          return 5;
      }

      else if(ch == 'X')
      {
          return 10;
      }

      else if(ch == 'L')
      {
          return 50;
      }

      else if(ch == 'C')
      {
          return 100;
      }

      else if(ch == 'D')
      {
          return 500;
      }

      else if(ch == 'M')
      {
          return 1000;
      }

      else
      {
          return 0;
      }
  }

  public static void main(String[] args)throws Exception
  {
        try
        {
            Scanner chase = new Scanner(new FileInputStream("RomanNumeralFile.txt"));
            while(chase.hasNext())
            {
                String tmp = chase.next();
                int arabNum = convert(tmp);
                if(arabNum == 0)
                {
                    System.out.println(tmp + " has a an invalid character");
                }
                else
                {
                    System.out.println(tmp + " = " + arabNum);
                }
            }
            System.out.println();
            Scanner chase2 = new Scanner(new FileInputStream("RomanNumeralDigitFile.txt"));
            while(chase2.hasNext())
            {
                int arabic = chase2.nextInt();
                if(Reverse(arabic).equals("Invalid Roman Number Value"))
                {
                    System.out.println(arabic + " has a an invalid character");
                }
                else
                {
                    System.out.println(arabic + " = " + Reverse(arabic));
                }
            }
        }

        catch(IOException e)
        {
            System.out.println("Invalid File Name");
        }
  }
}














import java.io.*;
import java.util.*;
/**
Chase Keskinyan
12/16/19
Mr.Goldman
Period 9 APCSA
 */
public class RomanNumeral
{
  static PrintStream richard;

  public static String Reverse(int input)
  {
    if (input < 1 || input > 3999)
        return "Invalid Roman Number Value";
    String s = "";
    while (input >= 1000) {
        s += "M";
        input -= 1000;        }
    while (input >= 900) {
        s += "CM";
        input -= 900;
    }
    while (input >= 500) {
        s += "D";
        input -= 500;
    }
    while (input >= 400) {
        s += "CD";
        input -= 400;
    }
    while (input >= 100) {
        s += "C";
        input -= 100;
    }
    while (input >= 90) {
        s += "XC";
        input -= 90;
    }
    while (input >= 50) {
        s += "L";
        input -= 50;
    }
    while (input >= 40) {
        s += "XL";
        input -= 40;
    }
    while (input >= 10) {
        s += "X";
        input -= 10;
    }
    while (input >= 9) {
        s += "IX";
        input -= 9;
    }
    while (input >= 5) {
        s += "V";
        input -= 5;
    }
    while (input >= 4) {
        s += "IV";
        input -= 4;
    }
    while (input >= 1) {
        s += "I";
        input -= 1;
    }
    return s;
}

  public static int convert(String r)
  {
    int count = 0;
    for(int i = 0; i < r.length() - 1; i++)
    {
        if(getDigitValue(r.charAt(i)) == 0)
        {
            return 0;
        }
        else if(getDigitValue(r.charAt(i)) < getDigitValue(r.charAt(i + 1)))
        {
            count -= getDigitValue(r.charAt(i));
        }
        else
        {
            count += getDigitValue(r.charAt(i));
        }
    }
    count += getDigitValue(r.charAt(r.length() - 1));
    return count;
  }

  public static int getDigitValue(char ch)
  {
      if(ch == 'I')
      {
          return 1;
      }

      else if(ch == 'V')
      {
          return 5;
      }

      else if(ch == 'X')
      {
          return 10;
      }

      else if(ch == 'L')
      {
          return 50;
      }

      else if(ch == 'C')
      {
          return 100;
      }

      else if(ch == 'D')
      {
          return 500;
      }

      else if(ch == 'M')
      {
          return 1000;
      }

      else
      {
          return 0;
      }
  }

  public static void main(String[] args)throws Exception
  {
        try
        {
            Scanner chase = new Scanner(new FileInputStream("RomanNumeralFile.txt"));
            while(chase.hasNext())
            {
                String tmp = chase.next();
                int arabNum = convert(tmp);
                if(arabNum == 0)
                {
                    System.out.println(tmp + " has a an invalid character");
                }
                else
                {
                    System.out.println(tmp + " = " + arabNum);
                }
            }
            System.out.println();
            Scanner chase2 = new Scanner(new FileInputStream("RomanNumeralDigitFile.txt"));
            while(chase2.hasNext())
            {
                int arabic = chase2.nextInt();
                if(Reverse(arabic).equals("Invalid Roman Number Value"))
                {
                    System.out.println(arabic + " has a an invalid character");
                }
                else
                {
                    System.out.println(arabic + " = " + Reverse(arabic));
                }
            }
        }

        catch(IOException e)
        {
            System.out.println("Invalid File Name");
        }
  }
}