scala 数字阶乘

Factorial of a number(n!) is the product of all positive numbers less than or equal to that number.

数字的阶乘(n！)是所有小于或等于该数字的正数的乘积。

The formula for factorial of a number is,

数字阶乘的公式是，

n! = n * (n-1) * (n-2) * ... * 2 * 1    n! = 1 if n = 1 or 0

Based on the above formula we can generate a recursive formula,

根据上述公式，我们可以生成一个递归公式，

n! = n * (n-1)!

Given a number, we have to find its factorial.

给定一个数字，我们必须找到它的阶乘。

Example:

例：

Input:     n = 6    Output:     n! = 720     Explanation:    6! = 6*5*4*3*2*1 = 720

The program will use this formula to find the factorial. As find factorial is a repetitive process. We have two methods to solve this problem,

程序将使用此公式查找阶乘。 发现阶乘是一个重复的过程。 我们有两种方法可以解决此问题，

1. Using iteration

   使用迭代

2. Using recursion

   使用递归

1)递归方法查找数字的阶乘 (1) Recursive Approach to find factorial of a number)

In recursion, we will call the same method multiple times until a condition is not satisfied.

在递归中，我们将多次调用同一方法，直到不满足条件为止。

Here, we will call the function factorial(n) in the following way:

在这里，我们将通过以下方式调用函数factorial(n) ：

Program:

程序：

object myObject {
       def factorialRec(n: Int): Int ={
           if(n <= 1)            return 1        return n * factorialRec(n-1)    }        def main(args: Array[String]) {
           val n = 6        println("The factorial of " + n + " is " + factorialRec(n))    }}

Output

输出量

The factorial of 6 is 720

2)迭代方法来找到数字的阶乘 (2) Iterative approach to find factorial of a number)

In iteration, we will loop over a sequence of numbers and multiply the number to result variable to find factorial.

在迭代中，我们将遍历数字序列，并将数字乘以结果变量以找到阶乘。

Program:

程序：

object myObject {
       def factorialIt(n: Int): Int ={
          var factorial = 1       for(i <- 1 to n)            factorial *= i        return factorial    }        def main(args: Array[String]) {
           val n = 6        println("The factorial of " + n + " is " + factorialIt(n))            }}

Output

输出量

The factorial of 6 is 720

翻译自:

scala 数字阶乘