Java兩種方法計算出階乘尾部連續0的個數

import java.util.Scanner;
import java.math.BigDecimal; 
import java.text.DecimalFormat; 
public class jc{
 public static void main(String args[]){
 Scanner reader = new Scanner(System.in);
 DecimalFormat a = new DecimalFormat("#");
 int num;
 num = reader.nextInt();
 double sum=1;
 for(int i=2;i<=num;i++){
 sum*=i;
 }
 //System.out.println(sum);
 //System.out.println(cal_the_number_of_zero(sum+""));
 System.out.println(a.format(sum));
 System.out.println(cal_the_number_of_zero(a.format(sum)));
 }
 public static int cal_the_number_of_zero(String str){
 int num=0;
 for(int i=0;i<str.length();i++){
  
 if(str.charAt(i)=='0'){
 num++; 
 }
 else{num=0;} 
 }
 return num; 
 }
}

import java.util.Scanner;

public class Main{ 
 public static void main(String[] args){
  Scanner sc = new Scanner(System.in);
  int n = sc.nextInt();
  int ret =0; 
  for(int i=n;i>=5;i--){
   int tmp =i;
   while(tmp%5==0){
    ret++;
    tmp=tmp/5;
   }
  }
  System.out.println(ret);
 }
}