Java 大数阶乘简单方法

import java.util.Scanner;

public class nc030 {
    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        Scanner cin = new Scanner(System.in);
        int n = cin.nextInt();
                
        long  start = System.currentTimeMillis(); 
        
        int[] date = new int[100000];// 用数组存放结果
        date[1] = 1;
        int weishu = 1; // 求出来的值的位数
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= weishu; j++) {
                date[j] = date[j] * i;
            }
            // 确保除最高位外的每位不大于9
            for (int j = 1; j < weishu; j++) {
                if (date[j] >= 10) {
                    date[j + 1] += date[j] / 10;
                    date[j] = date[j] % 10;
                }
            }
            // 确保最高位不大于9
            while (date[weishu] >= 10) {
                weishu++;
                date[weishu] += date[weishu - 1] / 10;
                date[weishu - 1] = date[weishu - 1] % 10;
            }
        }
        System.out.println(n+"的阶乘耗时："+(System.currentTimeMillis()-start)+"毫秒");
        // 输出数组结果
        for (int k = weishu; k >= 1; k--) {
            System.out.print(date[k]);
        }
    }
}