Using Saffron to solve the Subset Sum problem

The following is an example of how Saffron can be used to solve the Subset Sum problem: Given a set of nonnegative integers A and a nonnegative integer B, is there a subset A' ⊆ A such that the sum of the integers in A' equals exactly B?

JAVA CODE:

SubsetSumDemo.java

package showcase.subsetsum;

import java.util.ArrayList;
import naturalnumbers.ConditionalAdder;
import naturalnumbers.NaturalNumber;
import naturalnumbers.NaturalNumberFixer;
import bits.BooleanLiteral;
import bits.Conjunction;
import bits.IBitString;
import bits.INaturalNumber;
import bits.IProblem;
import bits.IProblemMessage;
import bits.Problem;
import bitstrings.BitString;

/**
 * Finds a subset of integers that sums to <code>desiredSum,</code> which in
 * this example is 171.
 */
public class SubsetSumDemo
{
public static void main(String[] args) throws Exception
{
/**
* Set Java variables:
*/

int B = 171;

Integer[] A = new Integer[]
{ 99, 92, 93, 85, 35, 27, 9, 2, 88, 90, 90, 1, 83, 45, 63, 83, 33, 21 };

int maxSum = 0;
for (int i = 0; i < A.length; i++)
maxSum += A[i];

/**
* Set globals:
*/

NaturalNumber.setLargestNaturalNumber(maxSum);

/**
* Create Saffron objects and arrays:
*/

INaturalNumber[] dataNNarry = new INaturalNumber[A.length];
IBitString membership = new BitString(A.length);
IProblem[] r = new IProblem[A.length];
INaturalNumber W = new NaturalNumber();
for (int i = 0; i < A.length; i++)
{
dataNNarry[i] = new NaturalNumber();
}

/**
* Create problems which constrain the values of these Saffron objects:
*/

for (int i = 0; i < A.length; i++)
{
r[i] = new NaturalNumberFixer(dataNNarry[i], A[i]);
}
IProblem rArray = new Conjunction(r);
IProblem fixW = new NaturalNumberFixer(W, B);
IProblem cAdd = new ConditionalAdder(dataNNarry, membership, W);

/**
* Create the IProblem of satisfying all of these constraining problems:
*/

IProblem problem = new Conjunction(rArray, fixW, cAdd);

/**
* Solve the IProblem:
*/

IProblemMessage s = problem.findModel(Problem.defaultSolver());
if (s.getStatus() == IProblemMessage.SATISFIABLE
&& s.getLiterals().size() > 0)
{
BooleanLiteral.interpret(s.getLiterals());
ArrayList<Integer> Aprime = new ArrayList<Integer>();
for (int i = 0; i < membership.size() - 1; i++)
if (membership.getBooleanVariable(i).getValue())
Aprime.add(A[i]);
for (int i = 0; i < Aprime.size() - 1; i++)
System.out.print(Aprime.get(i) + " + ");
System.out.print(Aprime.get(Aprime.size() - 1) + " = "
+ B);
}
else
System.out.println("No solution.");
}
}

OUTPUT:

93 + 35 + 9 + 1 + 33 = 171