jiecheng.java~1~

小程序

package mypackage;

import java.math.BigInteger;
import java.util.*;

public class JieCheng {




 protected static ArrayList table = new ArrayList();
 static {
   table.add(BigInteger.valueOf(1));
 }

 public static synchronized BigInteger factorial(int x){
  if(x<0) throw new IllegalArgumentException("x must be non-negative");
  for(int size = table.size();size<=x;size++){
      BigInteger lastfact = (BigInteger)table.get(size-1);
      BigInteger nextfact = lastfact.multiply(BigInteger.valueOf(size));
      table.add(nextfact);
      }
      return (BigInteger) table.get(x);
  }

  public static void main(String args[]){
      int i=60;
      System.out.println(factorial(i));
  }
}