蓝桥杯练习题阶乘计算

package Basic_VIP;



import java.util.ArrayList;

import java.util.Scanner;

public class Basic_30 {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

        int n = in.nextInt();

        ArrayList<Integer> alist = new ArrayList<>();

        alist.add(1);

        for (int i=1;i<=n;i++){

            int size = alist.size();

            for (int j=0;j<size;j++){

//                先把每一位乘以i，再进行进位

                int temp = alist.get(j);

                temp *= i;

                alist.set(j,temp);

            }

            for (int m=0;m<size;m++){

                int temp1 = alist.get(m);

                if (temp1 > 10){

                    alist.set(m,temp1%10);

                    int tempResult = temp1/10;

                    if (size <= m+1){

                        alist.add(tempResult);

                    }else{

                        int temp2 = alist.get(m+1);

                        alist.set(m+1,temp2+tempResult);

                    }

                }else{

                    alist.set(m,temp1);

                }

            }

        }

        for (int i=alist.size()-1;i>-1;i--){

            System.out.print(alist.get(i));

        }

    }

}