Java 組合數算法

import java.util.*;

public class Combination
{
	public static void main(String[] args)
	{
		Vector testData = new Vector(Arrays.asList(1, 2, 3, 4, 5, 6));
		Vector results = getAllCombinations(testData);
		for(int i=0; i<results.size(); i++)
			System.out.println(results.elementAt(i));
	}

	public static Vector getAllCombinations(Vector data)
	{
		Vector allCombinations = new Vector();
		for(int i=1; i<=data.size(); i++)
		{
			Vector initialCombination = new Vector();
			allCombinations.addAll(getAllCombinations(data, i));
		}

		return allCombinations;
	}

	public static Vector getAllCombinations(Vector data, int length)
	{
		Vector allCombinations = new Vector();
		Vector initialCombination = new Vector();
		combination(allCombinations, data, initialCombination, length);
		return allCombinations;
	}

	private static void combination(Vector allCombinations, Vector data, 
		Vector initialCombination, int length)
	{
		if(length == 1)
		{
			for(int i=0; i<data.size(); i++)
			{
				Vector newCombination = new Vector(initialCombination);
				newCombination.add(data.elementAt(i));
				allCombinations.add(newCombination);
			}
		}

		if(length > 1)
		{
			for(int i=0; i<data.size(); i++)
			{
				Vector newCombination = new Vector(initialCombination);
				newCombination.add(data.elementAt(i));

				Vector newData = new Vector(data);
				for(int j=0; j<=i; j++)
					newData.remove(data.elementAt(j));

				combination(allCombinations, newData, newCombination, length - 1);
			}
		}
	}
}

轉載一個兄弟的組合算法:

轉自：http://www.iteye.com/topic/343282