Java两种方法计算出阶乘尾部连续0的个数

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);

  }

}