ScratchPad.java

public class ScratchPad {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		q11();
	}
	
	static int[] input = {11,9,9,12,12,12,12,9,9,11};
	static int[] M = new int[input.length+1];

	static int r = 1;
	static int c=10;	
	
	public static void q11()
	{
		for (int i = 1; i < M.length; i++)
		{
			int s_i = input[i-1];
			int A = r * s_i + M[i-1];
			int B = 4*c + M[limit(i-4)];
			if (A < B)
				M[i] = A;
			else
				M[i] = B;
		}
		
		PrintSolution (M.length-1);
	}
	
	private static void PrintSolution (int i)
	{
		if (i < 1) return;
		int s_i = input[i-1];
		int A = r * s_i + M[i-1];
		int B = 4*c + M[limit(i-4)];
		if (A < B)
		{
			System.out.print("A");
			PrintSolution(i-1);
		}
		else
		{
			System.out.print("BBBB");
			PrintSolution(i-4);
		}
	}
	
	private static int limit(int i)
	{
		if (i < 0)
			return 0;
		return i;
	}

}