算法第四版1.1.20

package com.zzh;

import edu.princeton.cs.algs4.StdIn;
import edu.princeton.cs.algs4.StdOut;

public class Test {

    public static void main(String[] args) {
        int n=StdIn.readInt();
        StdOut.printf("%.1f\n",Math.log(fac(n)));
    }
    public static double fac(int n) {
        double x;
        if(n==1) return 1;
        else return n*fac(n-1);
        
    }
}