//
// Konwersja z i na system dziesietny
//
// www.algorytm.org
// (c)2006 by Tomasz Lubinski
//


public class Systemy {

	private static final int MAX_BASE = 36;
	private static final String pattern = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";


	//	returns converted n or null if an error occurs
	public static String convertTo(int n, int base)
	{
	   String result = "";

	   //base is too big or too small
	   if ((base > MAX_BASE) || (base < 2))
	      return null;

	   //n is equal to 0, do not process, return "0"
	   if (n == 0)
	      return "0";

	   //process until n > 0
	   while (n>0)
	   {
	      result = pattern.charAt(n % base) + result;
	      n /= base;
	   }

	   return result;
	}

	//	return value of x or -1 if an error occurs
	private static int valueOf(char x, int base)
	{
	   for (int i=0; i<base; i++)
	   {
	      if (x == pattern.charAt(i))
	      {
	         return i;
	      }
	   }
	   return -1;
	}

	//	returns converted n or 0 if an error occurs
	public static int convertFrom(String n, int base)
	{
	   int i, x;
	   int p = 1;
	   int result = 0;

	   //base is too big or too small
	   if ((base > MAX_BASE) || (base < 2))
	      return 0;

	   n = n.toUpperCase();

	   for (i=n.length()-1; i>=0; i--)
	   {
	      x = valueOf(n.charAt(i), base);
	      if (x < 0)
	      {
	         return 0;
	      }
	      result += (x * p);
	      p *= base;
	   }

	   return result;
	}
	
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		   System.out.println("3568 w systemie dwojkowym = " + convertTo(3568, 2));

		   System.out.println("3568 w systemie trojkowym = " + convertTo(3568, 3));

		   System.out.println("3568 w systemie osemkowym = " + convertTo(3568, 8));

		   System.out.println("3568 w systemie szesnastkowym = " + convertTo(3568, 16));

		   System.out.println("3568 w systemie dwudziestkowym = " + convertTo(3568, 20));

		   System.out.println("100010010 w systemie dwojkowym to " + convertFrom("100010010", 2) + " w systemie dziesietnym");

		   System.out.println("7542 w systemie ósemkowym to " + convertFrom("7542", 8) + " w systemie dziesietnym");

		   System.out.println("E854 w systemie szesnastkowym to " + convertFrom("E854", 16) + " w systemie dziesietnym");
	}

}