//
// Given an instance, is there a partion +/- 1?
//
import org.chocosolver.solver.Model;
import org.chocosolver.solver.Solver;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.search.strategy.Search;

public class Partition {

    int n;
    Model model;
    Solver solver;
    IntVar[] D;
    
    Partition(int[] w){
		n = w.length;
		model = new Model("Partition");
		solver = model.getSolver();
	
		int total = 0;
		for (int x : w) total = total + x;
	
		D = model.intVarArray("D",n,0,1); // decision ... left or right?      
		model.scalar(D,w,"=",total/2).post();
    }

    boolean solve(){
		solver.setSearch(Search.minDomUBSearch(D)); // take 1 then 0      
		return solver.solve();
    }

    long stats(){
		return solver.getMeasures().getNodeCount();
    }
}