全排列：

       设R=｛r_1,r_2,r₃……r_n｝是要排列的n个元素，R_i=R-｛r_i｝。集合X中元素的全排列记perm(X)。

       源代码：

import java.io.*;
import java.util.*;
 
 
public class SF_Quanpailie
{
       public static void main(String[] args)
       {
              int list[]={1,2,3,4};
              perm(list,0,4);
       }
 
       public static void  swap(int[] a,int i,int j){
              int temp=a[i];
              a[i]=a[j];
              a[j]=temp;
       }
 
       public static void perm(int[] list,int k,int m){
              if (k==m)
              {
                     for (int i=0; i<m;i++ )
                     {
                            System.out.print(list[i]);
                     }
                     System.out.println();
              }else {
                     for (int i=k;i<m ;i++ )
                     {
                            swap(list,k,i);
                            perm(list,k+1,m);
                            swap(list,k,i);
                     }
              }
       }
}

结果：