/*
 * Zorbage: an algebraic data hierarchy for use in numeric processing.
 *
 * Copyright (C) 2016-2020 Barry DeZonia
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package nom.bdezonia.zorbage.algorithm;

import nom.bdezonia.zorbage.algebra.Addition;
import nom.bdezonia.zorbage.algebra.Algebra;
import nom.bdezonia.zorbage.algebra.ModularDivision;
import nom.bdezonia.zorbage.algebra.Multiplication;
import nom.bdezonia.zorbage.algebra.Unity;

/**
 * 
 * @author Barry DeZonia
 *
 */
public class Combinations {

	// do not instantiate
	
	private Combinations() { }
	
	/**
	 * 
	 * @param algebra
	 * @param n
	 * @param result
	 */
	public static <T extends Algebra<T,U> & Unity<U> & Addition<U> & Multiplication<U> & ModularDivision<U>, U>
		void compute(T algebra, int n, int k, U result)
	{
		// combos = n! / ((k)! (n-k)!)
		U tmp = algebra.construct();
		U nFact = algebra.construct();
		U kFact = algebra.construct();
		U n_minus_k_Fact = algebra.construct();
		Factorial.compute(algebra, n, nFact);
		Factorial.compute(algebra, k, kFact);
		Factorial.compute(algebra, n-k, n_minus_k_Fact);
		algebra.div().call(nFact, kFact, tmp);
		algebra.div().call(tmp, n_minus_k_Fact, result);
	}
}

/*
 * Zorbage: an algebraic data hierarchy for use in numeric processing.
 *
 * Copyright (C) 2016-2020 Barry DeZonia
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package nom.bdezonia.zorbage.algorithm;

import nom.bdezonia.zorbage.algebra.Addition;
import nom.bdezonia.zorbage.algebra.Algebra;
import nom.bdezonia.zorbage.algebra.ModularDivision;
import nom.bdezonia.zorbage.algebra.Multiplication;
import nom.bdezonia.zorbage.algebra.Unity;

/**
 * 
 * @author Barry DeZonia
 *
 */
public class Combinations {

	// do not instantiate
	
	private Combinations() { }
	
	/**
	 * 
	 * @param algebra
	 * @param n
	 * @param k
	 * @param result
	 */
	public static <T extends Algebra<T,U> & Unity<U> & Addition<U> & Multiplication<U> & ModularDivision<U>, U>
		void compute(T algebra, int n, int k, U result)
	{
		// combos = n! / ((k)! (n-k)!)
		U tmp = algebra.construct();
		U nFact = algebra.construct();
		U kFact = algebra.construct();
		U n_minus_k_Fact = algebra.construct();
		Factorial.compute(algebra, n, nFact);
		Factorial.compute(algebra, k, kFact);
		Factorial.compute(algebra, n-k, n_minus_k_Fact);
		algebra.div().call(nFact, kFact, tmp);
		algebra.div().call(tmp, n_minus_k_Fact, result);
	}
}

Fix some javadoc