QuestionB.java

package Q8_05_Recursive_Multiply;

public class QuestionB {

	public static int counter = 0;
	
	public static int sum(int x, int y) {
		counter += 1;
		return x + y;
	}
	
	public static int minProduct(int smaller, int bigger, int[] memo) {
		if (smaller == 0) {
			return 0;
		} else if (smaller == 1) {
			return bigger;
		} else if (memo[smaller] > 0) {
			return memo[smaller];
		}
			
		/* Compute half. If uneven, compute other half. If even,
		 * double it. */
		int s = smaller >> 1; // Divide by 2
		int side1 = minProduct(s, bigger, memo); // Compute half
		int side2 = side1;
		if (smaller % 2 == 1) {
			counter++;
			side2 = minProduct(smaller - s, bigger, memo);
		}
		
		/* Sum and cache.*/
		counter++;
		memo[smaller] = side1 + side2; 
		return memo[smaller];
	}
	
	public static int minProduct(int a, int b) {
		int bigger = a < b ? b : a;
		int smaller = a < b ? a : b;
		
		int memo[] = new int[sum(smaller, 1)];
		return minProduct(smaller, bigger, memo);
	}
	
	public static void main(String[] args) {
		int a = 13494;
		int b = 22323;
		int product = a * b;
		int minProduct = minProduct(a, b);
		if (product == minProduct) {
			System.out.println("Success: " + a + " * " + b + " = " + product);
		} else {
			System.out.println("Failure: " + a + " * " + b + " = " + product + " instead of " + minProduct);
		}
		System.out.println("Adds: " + counter);
	}

}