1309 : 팩토리얼

import java.util.Scanner;
 
public class Main {
 
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner scan = new Scanner(System.in);
         
        int n;
        int i, j;
         
        n = scan.nextInt();
         
        long res = f(n);
        System.out.println(res);
         
    }
     
    private static long f(int a) {
        if (a <= 1) {
            System.out.printf("1! = 1\n");
            return 1;
        }
        System.out.printf("%d! = %d * %d!\n", a, a, a - 1);
         
        return f(a - 1) * a;
    }
 
}

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