阶乘,该怎么解决

阶乘
计数100的阶乘，结果取近似值或者精确值都可以
java程序实现

[解决办法]
[code=Java][/code]
public static void main(String[] args){
Scanner scan=new Scanner(System.in);
System.out.println("请输入一个整数：");
long n=scan.nextLong();
long sum=1;
for(long i=1;i<=n;i++){
sum*=i;
}
System.out.println("n的阶乘是："+sum);
}
[解决办法]

Java code

import java.math.BigInteger;import java.util.ArrayList; public class NewClass {    protected static ArrayList alist = new ArrayList();    static {        alist.add(BigInteger.valueOf(1));    }    /**     * Creates a new instance of factorial     */    public static synchronized BigInteger factorial(int x) {        if (x < 0) {            throw new IllegalArgumentException("x must be non-negative.");        }        for (int size = alist.size(); size <= x; size++) {            BigInteger lastfact = (BigInteger) alist.get(size - 1);            BigInteger nextfact = lastfact.multiply(BigInteger.valueOf(size));            alist.add(nextfact);        }        return (BigInteger) alist.get(x);    }    public static void main(String[] args) {                    System.out.println("100 != " + factorial(100));           }}