// File Problem.java

public interface Problem {}

// File Solution.java

public interface Solution {}

// File DivConqTemplate.java

abstract public class DivConqTemplate
{
    public final Solution solve (Problem p)
    {   Problem[] pp;
        if (isSimple(p))
        {   return simplySolve(p);   }
        else
        {   pp = decompose(p);   }
        Solution[] ss = new Solution[pp.length];
        for (int i = 0; i < pp.length; i++) 
        {   ss[i] = solve(pp[i]);   }
        return combine(p,ss);
    }
     
    abstract protected boolean isSimple (Problem p);
    abstract protected Solution simplySolve (Problem p);
    abstract protected Problem[] decompose (Problem p);
    abstract protected Solution combine (Problem p, Solution[] ss);
}

// File DivConqContext.java

public final class DivConqContext
{    
    public DivConqContext (DivConqStrategy dc)
    {   this.dc = dc;   }

    public Solution solve (Problem p)
    {   Problem[] pp;
        if (dc.isSimple(p))
        {   return dc.simplySolve(p); }
        else
        {   pp = dc.decompose(p); }
        Solution[] ss = new Solution[pp.length];
        for (int i = 0; i < pp.length; i++)
        {   ss[i] = solve(pp[i]);   } 
        return dc.combine(p, ss);
    }

    public void setAlgorithm (DivConqStrategy dc)
    {   this.dc = dc;   }

    private DivConqStrategy dc;
}

// File DivConqStrategy.java

abstract public class DivConqStrategy
{   
    abstract public boolean isSimple (Problem p);
    abstract public Solution simplySolve (Problem p);
    abstract public Problem[] decompose (Problem p);
    abstract public Solution combine (Problem p, Solution[] ss);
}