给定10个数字，列出其所有组合!不能重复

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

import java.util.Scanner;

import java.util.TreeSet;



public class Combination {

	private static int NUM = 0;

	

	public static void main(String[] args) {

		Scanner input = new Scanner(System.in);

		System.out.println("请输入X个数，用逗号分割：");

		String str = input.nextLine();

		String[] datas = str.split(",");

		System.out.println("请输入数字Y:");

		NUM = input.nextInt();

		if (NUM > datas.length) {

			System.out.println("输入的Y必须小于等于X!");

			return;

		}

		combine(Arrays.asList(datas));

	}



	private static void combine(List<String> datas) {

		TreeSet<String> set = new TreeSet<String>();

		for(String str : datas) {

			set.add(str);

		}

		

		ArrayList<TreeSet<String>> subset = getSubset(set);

		

		for(TreeSet<String> ts : subset) {

			System.out.println(ts);

		}

	}

	

	public static String[] getBinaryValue(TreeSet<String> set) {

		int size = set.size();

		int m = (int) Math.pow(2, size) - 1;

		String[] result = new String[m + 1];

		for (int i = m; i > -1; i--) {

			StringBuffer sb = new StringBuffer(Integer.toBinaryString(i));

			int length = sb.length();

			if (length < size) {

				for (int j = 0; j < size - length; j++) {

					sb.insert(0, "0");

				}

			}

			result[i] = sb.toString();

		}

		return result;

	}



	public static ArrayList<TreeSet<String>> getSubset(TreeSet<String> set) {

		ArrayList<TreeSet<String>> result = new ArrayList<TreeSet<String>>();

		String[] items = new String[set.size()];

		int i = 0;

		for (String item : set) {

			items[i++] = item;

		}

		String[] binaryValue = getBinaryValue(set);

		for (int j = 0; j < binaryValue.length; j++) {

			String value = binaryValue[j];

			TreeSet<String> subset = new TreeSet<String>();

			for (int k = 0; k < value.length(); k++) {

				if (value.charAt(k) == '1')

					subset.add(items[k]);

			}

			if(subset.size() == NUM)

				result.add(subset);

		}



		return result;

	}

}

import java.util.ArrayList;   

import java.util.Arrays;   

import java.util.List;   

import java.util.Scanner;

public class FullSort {   

    //将NUM设置为待排列数组的长度即实现全排列   

    private static int NUM = 0;   

  

    /**  

     * 递归算法：将数据分为两部分，递归将数据从左侧移右侧实现全排列  

     *  

     * @param datas  

     * @param target  

     */  

 

    private static void sort(List datas, List target) {   

        if (target.size() == NUM) {   

            for (Object obj : target)   

                System.out.print(obj);   

            System.out.println();   

            return;   

        }   

        for (int i = 0; i < datas.size(); i++) {   

            List newDatas = new ArrayList(datas);   

            List newTarget = new ArrayList(target);   

            newTarget.add(newDatas.get(i));   

            newDatas.remove(i);   

            sort(newDatas, newTarget);   

        }   

    }   

  

    public static void main(String[] args) {   

    	Scanner input = new Scanner(System.in);

    	System.out.println("请输入X个数，用逗号分割：");

    	String str = input.nextLine();

        String[] datas = str.split(",");   

        System.out.println("请输入数字Y:");

        NUM = input.nextInt();

        if(NUM > datas.length) {

        	System.out.println("输入的Y必须小于等于X!");

        	return;

        }

        sort(Arrays.asList(datas), new ArrayList());   

    }   

  

}