Encuentra el término N de la serie 1, 1, 2, 6, 24…

Dado un número N. La tarea es escribir un programa para encontrar el N-ésimo término en la siguiente serie: 
 

1, 1, 2, 6, 24…

Ejemplos: 
 

Input: 3
Output: 2
For N = 3
Nth term = (N-1)!
         = 2
Input: 5
Output: 24

El enésimo término de la serie viene dado por la siguiente fórmula: 
 

Nth term = ( N-1)! 

A continuación se muestra la implementación requerida: 
 

// CPP program to find N-th term of the series:
// 1, 1, 2, 6, 24...
#include <iostream>
using namespace std;
 
// calculate Nth term of series
int nthTerm(int N)
{
    if (N <= 1)
        return 1;
 
    int i, fact = 1;
    for (i = 1; i < N; i++)
        fact = fact * i;
 
    return fact;
}
 
// Driver Function
int main()
{
    int N = 3;
 
    cout << nthTerm(N);
 
    return 0;
}

// Java program to find the Nth term
import java.io.*;
 
// calculate Nth term of this series
// 1, 1, 2, 6, 24...
class Nth {
    public int nthTerm(int N)
    {
        // By using above formula
        if (N <= 1)
            return 1;
 
        int i, fact = 1;
        for (i = 1; i < N; i++)
            fact = fact * i;
 
        return fact;
    }
}
// Main class for main method
class GFG {
 
    public static void main(String[] args)
    {
 
        int N = 3;
 
        // create object of Class Nth
        Nth a = new Nth();
 
        // call and print Nth term
        System.out.println(a.nthTerm(N));
    }
}

# Python 3 program to find
# N-th term of the series:
# 1, 1, 2, 6, 24...
 
# Function to calculate
# Nth term of series
def nthTerm(n) :
 
    if n <= 1 :
        return 1
 
    fact = 1
    for i in range(1, N) :
        fact = fact * i
 
    return fact
 
# Driver code
if __name__ == "__main__" :
 
    N = 3
 
    # function calling
    print(nthTerm(N))
 
# This code is contributed
# by ANKITRAI1

// C# program to find the
// Nth term of the series
// 1, 1, 2, 6, 24...
using System;
 
// calculate Nth term
class GFG
{
public int nthTerm(int N)
{
    // By using above formula
    if (N <= 1)
        return 1;
 
    int i, fact = 1;
    for (i = 1; i < N; i++)
        fact = fact * i;
 
    return fact;
}
 
// Driver Code
public static void Main()
{
    int N = 3;
 
    // create object of Class GFG
    GFG a = new GFG();
 
    // call and print Nth term
    Console.Write(a.nthTerm(N));
}
}
 
// This code is contributed
// by ChitraNayal

<?php
// PHP program to find N-th
// term of the series:
// 1, 1, 2, 6, 24...
 
// calculate Nth term of series
function nthTerm($N)
{
    if ($N <= 1)
        return 1;
 
    $fact = 1;
    for ($i = 1; $i < $N; $i++)
        $fact = $fact * $i;
 
    return $fact;
}
 
// Driver Code
$N = 3;
 
echo nthTerm($N);
 
// This code is contributed
// by ChitraNayal
?>

<script>
 
// JavaScript program to find N-th term of the series:
// 1, 1, 2, 6, 24...
 
// calculate Nth term of series
function nthTerm( N)
{
    if (N <= 1)
        return 1;
 
    let i, fact = 1;
    for (i = 1; i < N; i++)
        fact = fact * i;
 
    return fact;
}
 
// Driver Function
    let N = 3;
 
    document.write(nthTerm(N));
     
// This code contributed by Rajput-Ji
 
</script>

2

Complejidad de tiempo: O(N), donde N representa el entero dado.
Espacio auxiliar: O(1), no se requiere espacio adicional, por lo que es una constante.