/*
 * Permutation.java
 *
 * Created on June 27, 2006, 2:10 PM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package permutation;

import java.util.logging.FileHandler;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.jws.WebResult;
import javax.jws.WebService;
import javax.jws.WebMethod;
import javax.jws.WebParam;

   
    
    @WebService(targetNamespace="www.permutation.example")
public class Permutation {
    
    private static Logger m_logger;
  
        
    static {
        try
        {
            m_logger = Logger.getLogger("www.permutation.example");
            FileHandler fh = new FileHandler("c:/netbeans/projects/permutation.txt");
            m_logger.addHandler(fh);
        }
        catch(Throwable th)
        {
            
        }
    }
        /* Sample Web Service Operation */
    
    @WebMethod(operationName="computePermutations")
    @WebResult(name="combinations")
    public long compute(@WebParam(name="collectionSize") int n, @WebParam(name="itemsChosen") int r) {

        if (r > n) {
                throw new RuntimeException("Items chosen " + r + " must be less than or equal to collection size " + n);
        }
       

        long temp = 1;
        int j = 0;
        for(int i = n - r + 1; i <= n; i++)
        {
            temp *= i;
            temp /= ++j;
        }
        
        m_logger.log(Level.INFO, "The combinations for {0} choose {1} is {2}", new Object[]{Integer.valueOf(n),
            Integer.valueOf(r),Long.valueOf(temp)});
        
        return temp;
       
       
                
   }
    
   
}