CareerCup

<pre lang="java" line="1" title="CodeMonkey20076" class="run-this">class Caller {

/**
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
Caller c=new Caller();
System.out.print(c.convertToRoman(1681));
}
class Romans{
int deciValue;
char value;
Romans(int deciValue, char value){
this.deciValue=deciValue;
this.value=value;
}
}
public String convertToRoman(int num)
{
StringBuffer sb=new StringBuffer();
Romans[] romans = getRomans();
for(int i=0;i<romans.length;i++)
{
int count=num/romans[i].deciValue;
num=num-(romans[i].deciValue*count);
while(count !=0){
sb.append(romans[i].value);
count--;
}
}
return sb.toString();
}
private Romans[] getRomans() {
Romans roman1=new Romans(1000,'M');
Romans roman2=new Romans(500,'D');
Romans roman3=new Romans(100,'C');
Romans roman4=new Romans(50,'L');
Romans roman5=new Romans(10,'X');
Romans roman6=new Romans(5,'V');
Romans roman7=new Romans(1,'I');
Romans[] romans=new Romans[]{roman1,roman2,roman3,roman4,roman5,roman6,roman7};
return romans;
}

}
</pre><pre title="CodeMonkey20076" input="yes">1681
</pre>

private static string IntegerToRoman(int number)
        {
            // Validate
            if (number < 0 || number > 3999)
            {
                throw new ArgumentException("Value must be in the range 0 - 3,999.");
            }

            if (number == 0) return "N";

            // Set up key numerals and numeral pairs
            int[] values = new int[] { 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 };
            string[] numerals = new string[] { "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I" };

            StringBuilder result = new StringBuilder();

            // Loop through each of the values to diminish the number
            for (int i = 0; i < 13; i++)
            {
                // If the number being converted is less than the test value, append
                // the corresponding numeral or numeral pair to the resultant string
                while (number >= values[i])
                {
                    number -= values[i];
                    result.Append(numerals[i]);
                }
            }
            // Done
            return result.ToString();
        }

static string intToRoman(int num) 
        {  
            string roman = "";
            int h, t, o, th;
            string[] ones = {"","I","II","III","IV","V","VI","VII","VIII","IX"};
            string[] tens = { "", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC" };
            string[] hundreds = { "", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM" };
            string[] thousands = { "", "M", "MM", "MMM", "MMMM", "MMMMM" };   
            if (num <= 5000)
            {    
                th = num / 1000;
                num = num % 1000;
                h = num / 100;
                num = num % 100;
                t = num / 10;    
                o = num % 10;  
  
                roman = roman + thousands[th] + hundreds[h] + tens[t] + ones[o];  
            } 
            else 
            {
                roman = "Please enter a smaller number\n"; 
            }
        
            return roman; 
        }

Here's what I got in my first attempt, although I like manish's solution better -

public static String getRoman(int arabicNum) {
		StringBuilder roman = new StringBuilder();
		if(arabicNum < 1 || arabicNum > 3999) return roman.toString();
		
		if (arabicNum /1000 > 0) {
			int mCount = arabicNum/1000;
			arabicNum = arabicNum % 1000;
			for(int i = 0 ; i < mCount; ++i) {
				roman.append('M');
			}
			
		}
		
		if(arabicNum > 899) {
			roman.append("CM");
			arabicNum = arabicNum % 900;
		}
		
		
		if(arabicNum > 500) {
			roman.append("D");
			arabicNum = arabicNum % 500;
		}
		
		if(arabicNum > 399) {
			roman.append("CD");
			arabicNum = arabicNum % 400;
		}
		
		if(arabicNum > 99) {
			int numC = arabicNum / 100;
			for(int i = 0; i < numC; ++i) {
				roman.append('C');
			}
			arabicNum = arabicNum % 100;
		}
		
		if(arabicNum >89) {
			roman.append("XC");
			arabicNum = arabicNum % 90;
		}
		
		if(arabicNum > 49) {
			roman.append('L');
			arabicNum = arabicNum % 50;
		}
		
		if(arabicNum > 39) {
			roman.append("XL");
			arabicNum = arabicNum % 40;
		}
		
		if(arabicNum > 9) {
			int numX = arabicNum / 10;
			for(int i = 0; i < numX; ++i ) {
				roman.append('X');
			}
			arabicNum %= 10;
		}
		
		if (arabicNum > 8) {
			roman.append("IX");
			arabicNum %= 9;
		}
		
		if(arabicNum > 4) {
			roman.append('V');
			arabicNum %= 5;
		}
		
		if(arabicNum > 3) {
			roman.append("IV");
			arabicNum %= 4;
		}
		
		if(arabicNum > 0) {
			for(int i = 0; i < arabicNum; ++i) {
				roman.append('I');
			}
		}
		return roman.toString();
	}