함수 factorial()

1 개요

factorial()

FACT()

• 팩토리얼을 구하는 함수

2 테스트케이스

• factorial(0) = 1
• factorial(1) = 1
• factorial(2) = 2
• factorial(3) = 6
• factorial(4) = 24
• factorial(5) = 120
• factorial(6) = 720
• factorial(7) = 5040
• factorial(8) = 40320
• factorial(9) = 362880
• factorial(10) = 3628800

3 C

C factorial() 문서를 참고하십시오.

C

CPU

0.1s

MEM

18M

0.1s

Copy

#include <stdio.h>

long long factorial(int num) {
    if (num == 0) return 1;
    return num * factorial(num - 1);
}

int main() {
    printf("%lld\n", factorial(9));  // 362880
    printf("%lld\n", factorial(12)); // 479001600
}

362880
479001600

4 Excel

엑셀 FACT() 문서를 참고하십시오.

PHP

Copy

=FACT(4)
// 24

5 Java

Java

CPU

1.2s

MEM

71M

0.8s

Copy

public class MyClass {
    static int fact(int n) {
        int res = 1;
        for(int i=2; i<=n; i++) res *= i;
        return res;
    }
	public static void main(String args[]){
		System.out.println(fact(1)); // 1
		System.out.println(fact(2)); // 2
		System.out.println(fact(4)); // 24
		System.out.println(fact(8)); // 40320
		System.out.println(fact(9)); // 362880
		System.out.println(fact(10)); // 3628800
		System.out.println(fact(11)); // 39916800
		System.out.println(fact(12)); // 479001600
		System.out.println(fact(13)); // 1932053504 (wrong value, ≠ 6227020800)
		System.out.println(fact(14)); // 1278945280 (wrong value, ≠ 87178291200)
	}
}

1
2
24
40320
362880
3628800
39916800
479001600
1932053504
1278945280

6 JavaScript

자바스크립트 factorial() 문서를 참고하십시오.

JavaScript

Copy

function factorial(n) {
    var result = 1;
    for(var i=2; i<=n; i++) result *= i;
    return result;
}

7 Lua

Lua factorial() 문서를 참고하십시오.

lua

Copy

function factorial(n)
    if n == 0 then
        return 1
    end
    return n * factorial(n - 1)
end

8 Perl

Perl

Copy

sub factorial {
	my ($x, $result) = (shift, 1);
	$result *= $_ for (2 ... $x);
	return $result;
}

9 PHP

PHP factorial() 문서를 참고하십시오.

반복

PHP

Copy

function factorial($x) {
	$result = 1;
	for($i=2; $i<=$x; $i++) $result *= $i;
	return $result;
}
echo factorial(4);
# 24

재귀

PHP

Copy

function factorial($n) {
	if( $n <= 1 ) return 1;
	return $n * factorial($n-1);
}
echo factorial(4);
# 24

10 Python

파이썬 factorial() 문서를 참고하십시오.

Python

Copy

from math import factorial
print( factorial(4) )

Python

Copy

def factorial(x):
    result = 1
    for i in range(2,x+1):
        result *= i
    return result

11 R

R factorial() 문서를 참고하십시오.

R

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factorial(0)   ## [1] 1
factorial(1)   ## [1] 1
factorial(2)   ## [1] 2
factorial(3)   ## [1] 6
factorial(4)   ## [1] 24
factorial(5)   ## [1] 120
factorial(6)   ## [1] 720
factorial(10)  ## [1] 3628800
factorial(100) ## [1] 9.332622e+157
factorial(-1)  ## [1] NaN

12 같이 보기

• 팩토리얼
• 함수 nPr()
• 함수 nCr()