今天工作中遇到一个问题需要一个组合数算法。google了一会，没有找到合适的，于是就自己写了一个。主要是用了一个递归算法。发出来分享一下，有用的着的就拿去，觉得写得不好的就拍点砖，提点建议。
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);
}
}
}
}
测试结果：
[1]
[2]
[3]
[4]
[5]
[6]
[1, 2]
[1, 3]
[1, 4]
[1, 5]
[1, 6]
[2, 3]
[2, 4]
[2, 5]
[2, 6]
[3, 4]
[3, 5]
[3, 6]
[4, 5]
[4, 6]
[5, 6]
[1, 2, 3]
[1, 2, 4]
[1, 2, 5]
[1, 2, 6]
[1, 3, 4]
[1, 3, 5]
[1, 3, 6]
[1, 4, 5]
[1, 4, 6]
[1, 5, 6]
[2, 3, 4]
[2, 3, 5]
[2, 3, 6]
[2, 4, 5]
[2, 4, 6]
[2, 5, 6]
[3, 4, 5]
[3, 4, 6]
[3, 5, 6]
[4, 5, 6]
[1, 2, 3, 4]
[1, 2, 3, 5]
[1, 2, 3, 6]
[1, 2, 4, 5]
[1, 2, 4, 6]
[1, 2, 5, 6]
[1, 3, 4, 5]
[1, 3, 4, 6]
[1, 3, 5, 6]
[1, 4, 5, 6]
[2, 3, 4, 5]
[2, 3, 4, 6]
[2, 3, 5, 6]
[2, 4, 5, 6]
[3, 4, 5, 6]
[1, 2, 3, 4, 5]
[1, 2, 3, 4, 6]
[1, 2, 3, 5, 6]
[1, 2, 4, 5, 6]
[1, 3, 4, 5, 6]
[2, 3, 4, 5, 6]
[1, 2, 3, 4, 5, 6]
已有 3 人发表留言，猛击->>这里<<-参与讨论
JavaEye推荐