1.

package streetNumbers;
/**
 * FWP, Ausgewählte Probleme aus dem ACM Programming Contest, WS10/11
 * Problem: 138 Street Numbers
 * Link: http://uva.onlinejudge.org/index.php?option=com_onlinejudge&page=show_problem&problem=74
 *
 * @author Patrick Bédat
 * @version 1.0, 10/31/2010
 *
 * Method : Gaußsche Summenformel
 * Status : Accepted
 * Runtime: 1.080
 */
public class Main
{

	public static void main(String... args)
	{
		generateNumbers();
	}

	private static void generateNumbers()
	{
		long sumBefore = 1;
		int count = 0;

		for (int i = 2; count < 10; i++)
		{
			//fake determinant, missing division by 2
			Double determinant = Math.sqrt(1 + 8*(sumBefore*2+i));

			if(determinant - determinant.intValue() == 0)
			{
				count++;

				int result = ((int)(determinant-1))>>1;
				System.out.printf("%10d%10d%n",i,result);
			}

			sumBefore += i;
		}
	}
}



2. Martin Lambeck


package acm_138_street_numbers;

public class Main
{
	public static void main (String...args)
	{
		int found = 0;
		long start = 1;
		long end;
		
		System.out.println("6: " + find(6));
		
		while (found < 10)
		{
			start++;
			end = find(start);
			
			if (end != 0)
				System.out.println("" + start + " - " + end);
		}
	}
	
	static long sum (long n)
	{
		return (n * (n+1)) / 2;
	}
	
	static long find(long nr)
	{
		long togo = sum(nr);
		long n = nr-1;
		
		while (togo > 0)
		{
			n++;
			togo -= n;
		}
		
		return (togo == 0 ? n : 0);
	}
}

2.

/**
 * Angewandte Mathematik, SS09, IFB 2C 
 * ACM Problem #138 (Street Numbers)
 * Link: http://icpcres.ecs.baylor.edu/onlinejudge/index.php?option=com_onlinejudge&Itemid=8&category=3&page=show_problem&problem=74
 * 
 * @author David Leib
 * @author Julius Tschannerl
 * @version 1.0, 03/25/2009
 * 
 * Status : Accepted
 * Runtime: 2.3
 */
public class Main {
	
	public static void main(String... args)
	{
		int outputCount = 1;
		long sumBelow = 0;
		long end = 2;
		long sumAbove = 0;
		
		
		for (long i = 2; outputCount <= 10; i++)
		{
			sumBelow += (i-1);
			sumAbove -= (i);
			for (long j = (end+1); sumAbove < sumBelow; end++)
			{
				sumAbove += end;
			}
			if (sumAbove == sumBelow){
				System.out.printf("%10d%10d%n", i, end-1);
				outputCount++;
			}
			
		}
		System.exit(0);
		
	}
}