paizaラーニングレベルアップ問題集の「階乗の計算」「階乗の末尾に0はいくつ付く?」をやってみました。
問題
階乗の計算
階乗の末尾に0はいくつ付く?
方針
階乗の末尾に0はいくつ付くか、ですが、
- $5$の倍数を掛けると$0$が一つ付きます
- 更に$25(=5\times5)$の倍数を掛けると更に$0$が一つ（合計2つ）付きます
- 更に$125(=5\times5\times5)$の倍数を掛けると更に$0$が一つ（合計3つ）付きます
- 更に$625(=5\times5\times5\times5)$の倍数を掛けると更に$0$が一つ（合計4つ）付きます
「$N$を$5$で割った商を足して、$N$を$5$で割った商に置き換える」
操作を繰り返します。
C
階乗の計算
#include <stdio.h>
int main() {
int n;
scanf("%d", &n);
int factorial = n;
while (--n) factorial *= n;
printf("%d\n", factorial);
return 0;
}
階乗の末尾に0はいくつ付く?
#include <stdio.h>
int main() {
int n;
scanf("%d", &n);
int zero = 0;
while (n >= 5) {
n /= 5;
zero += n;
}
printf("%d\n", zero);
return 0;
}
C++
階乗の計算
#include <iostream>
using namespace std;
int main() {
int n;
cin >> n;
int factorial = n;
while (--n) factorial *= n;
cout << factorial << endl;
return 0;
}
階乗の末尾に0はいくつ付く?
#include <iostream>
using namespace std;
int main() {
int n;
cin >> n;
int zero = 0;
while (n >= 5) {
n /= 5;
zero += n;
}
cout << zero << endl;
return 0;
}
C#
階乗の計算
using System;
class Program
{
public static void Main()
{
int n = int.Parse(Console.ReadLine());
int factorial = 1;
for (int i = 1; i <= n; i++) factorial *= i;
Console.WriteLine(factorial);
}
}
階乗の末尾に0はいくつ付く?
using System;
class Program
{
public static void Main()
{
int n = int.Parse(Console.ReadLine());
int zero = 0;
while (n >= 5) {
n /= 5;
zero += n;
}
Console.WriteLine(zero);
}
}
Go
階乗の計算
package main
import "fmt"
func main() {
var n int
fmt.Scan(&n)
factorial := 1
for i := 1; i <= n; i++ {
factorial *= i
}
fmt.Println(factorial)
}
階乗の末尾に0はいくつ付く?
package main
import "fmt"
func main() {
var n int
fmt.Scan(&n)
zero := 0
for n >= 5 {
n /= 5
zero += n
}
fmt.Println(zero)
}
Java
階乗の計算
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
sc.close();
int factorial = 1;
for (int i = 1; i <= n; i++) factorial *= i;
System.out.println(factorial);
}
}
階乗の末尾に0はいくつ付く?
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
sc.close();
int zero = 0;
while (n >= 5) {
n /= 5;
zero += n;
}
System.out.println(zero);
}
}
JavaScript
階乗の計算
let n = Number(require("fs").readFileSync("/dev/stdin", "utf8"));
let factorial = n;
while (--n) factorial *= n;
console.log(factorial);
階乗の末尾に0はいくつ付く?
let n = Number(require("fs").readFileSync("/dev/stdin", "utf8"));
let zero = 0;
while (n >= 5) {
n = parseInt(n / 5);
zero += n;
}
console.log(zero);
Kotlin
階乗の計算
fun main() {
val n = readLine()!!.toInt()
var factorial = 1
for (i in 1..n) factorial *= i
println(factorial)
}
階乗の末尾に0はいくつ付く?
fun main() {
var n = readLine()!!.toInt()
var zero = 0
while (n >= 5) {
n /= 5
zero += n
}
println(n)
}
PHP
階乗の計算
<?php
$n = intval(fgets(STDIN));
$factorial = $n;
while (--$n) $factorial *= $n;
echo $factorial, PHP_EOL;
?>
階乗の末尾に0はいくつ付く?
<?php
$n = intval(fgets(STDIN));
$zero = 0;
while ($n >= 5) {
$n = intdiv($n, 5);
$zero += $n;
}
echo $zero, PHP_EOL;
?>
Perl
階乗の計算
my $n = int(<STDIN>);
my $factorial = $n;
while (--$n) {
$factorial *= $n;
}
print "$factorial$/";
階乗の末尾に0はいくつ付く?
my $n = int(<STDIN>);
my $zero = 0;
while ($n >= 5) {
$n = int($n / 5);
$zero += $n;
}
print "$zero$/";
Python3
階乗の計算
n = int(input())
factorial = 1
for i in range(1, n + 1):
factorial *= i
print(factorial)
階乗の末尾に0はいくつ付く?
n = int(input())
zero = 0
while n >= 5:
n //= 5
zero += n
print(zero)
Ruby
階乗の計算
n = gets.to_i
factorial = 1
(1..n).each do |i|
factorial *= i
end
p factorial
階乗の末尾に0はいくつ付く?
n = gets.to_i
zero = 0
while n >= 5
n /= 5
zero += n
end
p zero
Scala
階乗の計算
import scala.io.StdIn._
object Main extends App{
val n = readInt()
var factorial = 1
for (i <- 1 to n) factorial *= i
println(factorial)
}
階乗の末尾に0はいくつ付く?
import scala.io.StdIn._
object Main extends App{
var n = readInt()
var zero = 0
while (n >= 5) {
n /= 5
zero += n
}
println(zero)
}
Swift
階乗の計算
let n = Int(readLine()!)!
var factorial = 1
for i in 1...n {
factorial *= i
}
print(factorial)
階乗の末尾に0はいくつ付く?
var n = Int(readLine()!)!
var zero = 0
while n >= 5 {
n /= 5
zero += n
}
print(zero)