package MathMethod; //package name should begin with a lowercase character by convention
/**
 * Title: 排列问题递归算法
 * Description: 利用递归方法求解对象数组list[0:maxSize-1]的子数组list[k:m]的全排列
 * Copyright (c) 2005
 * Company: math
 * @author ql213
 */
public class arrangeArithmetic {  //class name should begin with an uppercase character by convention
 static int size; //要排序的元素个数
 static int Anum=0;
 public arrangeArithmetic(int i,int j)
 {
   if(i>j)
   {
       System.out.println("Please insure that your input[i,j]:i<=j!");
       return;
    }
   this.size=Math.abs(j-i)+1;
 }
 //交换对象数组的两个元素
 public static void swap(Object []a,int i, int j)
 {
   Object temp=a[i];
   a[i]=a[j];
   a[j]=temp;
 }
 public static void perm(Object []list,int k,int m) throws Exception
 {
   //产生list[k:m]的所有排列
   if(k==m)
   {
     //得到一种排列
     Anum++;
     System.out.print("Arrange: ");
     for(int i=m-size+1;i<=m;i++)
     {
       System.out.print(list[i]);
     }
     System.out.println(" ");
   }
   else
   {
      //按照前面的递归思想产生排列
      for(int i=k;i<=m;i++)
      {
        swap(list,k,i);
        perm(list,k+1,m);//递归求解
        swap(list,k,i);
      }
   }
 }
 public int ArrangeNum()
 {
   return Anum;//返回排列个数
 }
}