java排列组合算法代码实现

package com.zuidaima.test;
/**
*@author www.zuidaima.com
**/
public class Pailie {
	 public static void main(String[] args) {
	        int[] ia = {1, 2, 3, 4,5,6,7,8,9,10};
	        int n = 4;
	        System.out.println("排列结果 : ");
	        permutation("",ia, n);
//	        System.out.println("组合结果 : ");
//	        combination(ia, n);
	    }
	    public static void permutation(String s, int[] ia, int n) {
	        if(n == 1) {
	            for(int i = 0; i < ia.length; i++) {
	                System.out.println(s+ia[i]);
	            }
	        } else {
	            for(int i = 0; i < ia.length; i++) {
	                String ss = "";
	                ss = s+ia[i]+"";
	                //建立没有第i个元素的子数组
	                int[] ii = new int[ia.length-1];
	                int index = 0;
	                for(int j = 0; j < ia.length; j++) {
	                    if(j != i) {
	                        ii[index++] = ia[j];
	                    }
	                }
	                permutation(ss, ii, n-1);
	            }
	        }
	    }
	    public static void combination(int[] ia, int n) {
	        combination("", ia, n);
	    }
	    public static void combination(String s, int[] ia, int n) {
	        if(n == 1) {
	            for(int i = 0; i < ia.length; i++) {
	                System.out.println(s+ia[i]);
	            }
	        } else {
	            for(int i = 0; i < ia.length-(n-1); i++) {
	                String ss = "";
	                ss = s+ia[i]+", ";
	                //建立从i开始的子数组
	                int[] ii = new int[ia.length-i-1];
	                for(int j = 0; j < ia.length-i-1; j++) {
	                    ii[j] = ia[i+j+1];
	                }
	                combination(ss, ii, n-1);
	            }
	        }
	    }
}