biginteger_factorial.java

计算大数阶乘 采用java中的BigInteger类

import java.math.*;
import java.io.*;
class BigInteger_factorial
{

 
   public static void main(String args[])
   {
      int arr[]={0,0,0,0,0,0};
      BigInteger n1=new BigInteger("0");
      BigInteger n2=new BigInteger("10");
      BigInteger ONE=new BigInteger("1");
      

  try{
      InputStreamReader reader=new InputStreamReader(System.in);
      BufferedReader input =new BufferedReader(reader);
      for(int i=0;i<6;i++)
      {
         arr[i]=Integer.parseInt(input.readLine());
      }
     }      
             catch(NumberFormatException fe)
             {System.out.println("format error");}
             catch(IOException e)
             {System.out.println("IOException occur!!");}
      for(int j=0;j<6;j++)
      {
      n1=BigInteger.valueOf(arr[j]);
      BigInteger COUNT=new BigInteger("1");
      for(BigInteger i=ONE;(i.compareTo(n1))<=0;i=i.add(ONE))
      { 
        COUNT=COUNT.multiply(i);
      }

     
      System.out.println(COUNT);
      while((COUNT.remainder(n2).compareTo(BigInteger.ZERO))==0)    
      {
         COUNT=COUNT.divide(n2);
      }
      System.out.printf("%5d",arr[j]);
      System.out.print(" -> ");
      System.out.println(COUNT.remainder(n2));
      }

      }
}

   
//      System.out.println("十进制表示大数n1为："+n1.toString(10));
     
//      System.out.println("输入一个数以求其阶乘: ");

/*
import java.io.*;
import java.math.*;
public class BigInteger_factorial {
  public static void main(String[] args) throws IOException
   {
       BigInteger s = BigInteger.valueOf(1);
           for ( int i = 1;i<=1000 ; i++)
           {
               s = s.multiply(BigInteger.valueOf(i));
           }
       System.out.println(s);
   }    
}*/