Permutation.java

package com.seveniu;

import java.util.ArrayList;
import java.util.List;

public class Permutation {
    private int[] array; //传入数组
    private int num;  //从数组中选出n个数
    private int[] result = new int[num];  //将选出的n个数存入数组
    private int count = 0;

    private List<int[]> resultList = new ArrayList<int[]>();

    public Permutation(int[] array, int num) {
        this.array = array;
        this.num = num;
        this.result = new int[num];
    }

    public List<int[]> getResult() {  //5选3   从sum个数中选n个数
        return make(array.length,num);

    }
    public List<int[]> make(int sum , int n) {  //5选3   从sum个数中选n个数
        if (n > 0) {  //用来判断递归次数
            for (int i = array.length - sum; i < array.length; i++) {  //从length-sum开始循环
                result[this.num - n] = array[i]; //将结果存到数组中
                if (n == 1) {  //输出存放结果的数组
                    for (int number : result) {
                        System.out.print(number + " ");
                    }
                    System.out.println(";");
                    count++;  //统计排列总和
                    resultList.add(result);
                }

                sum--;  //每循环一次，总数减一

                make(sum, n - 1);  //开始下一层递归
            }
        }
        return resultList;
    }
}