Golang 如何执行nCr(r-combinations)

在本教程中，我们将在Golang编程语言中执行nCr(r-combinations)。nCr(r-combinations)的用例是找到可能排列的总数，其中顺序并不重要。换句话说，我们要从n个项目中选择顺序不重要的r个项目。本教程将包括两种在Golang编程语言中找到这个的方法。

解释

例如，对于n =5和r = 3

nCr = n!/ ( r!* ( n – r )!)

= 5!/ ( 3! * 2! )

= 120 / 12

= 10

算法

第1步 - 声明所有需要的变量来存储n、r、n阶乘、r阶乘和n-r阶乘。

第2步 --初始化n、r、n阶乘、r阶乘和n-r阶乘的值。

第3步 – 找到n、r和n-r的阶乘。

第4步 - 使用上述公式求出nCr。

第5步 - 打印结果。

例子

在这个例子中，我们将使用for循环查找nCr。

package main

// fmt package provides the function to print anything
import (
   "fmt"
)
func main() {

   // declaring the variables to store the value of n, r and answer
   var n, r, nFactorial, rFactorial, nminusrFactorial, answer int
   fmt.Println("Program to find the nCr using the for loop.")

   // initializing the value of n 
   n = 10

   // initializing the value of r
   r = 8
   nFactorial = 1

   // finding factorial of n
   for i := 1; i <= n; i++ {
      nFactorial = nFactorial * i
   }
   rFactorial = 1

   // finding factorial of r
   for i := 1; i <= r; i++ {
      rFactorial = rFactorial * i
   }
   nminusrFactorial = 1

   // finding factorial of n - r
   for i := 1; i <= n-r; i++ {
      nminusrFactorial = nminusrFactorial * i
   }

   // finding answer by using the formulae
   answer = nFactorial / (rFactorial * nminusrFactorial)

   // printing the result
   fmt.Println("The value of nCr with n =", n, "and r=", r, "is", answer)
}

输出

Program to find the nCr using the for loop.
The value of nCr with n = 10 and r= 8 is 45

算法

第1步 - 声明所有需要的变量，以存储n、r、n阶乘、r阶乘和n-r阶乘。

第2步 --初始化n、r、n阶乘、r阶乘和n-r阶乘的值。

第3步 – 在单独的函数中找到n、r和n-r的阶乘。

第4步 - 使用上述公式找到nCr。

第5步 - 打印结果。

例子

在这个例子中，我们使用单独的函数来寻找n、r和n-r的阶乘。

package main

// fmt package provides the function to print anything
import (
   "fmt"
)

// this is a recursive function of return type int

// which is returning the factorial of number

// passed in argument
func factorial(n int) int {
   if n == 1 {
      return 1
   }
   return factorial(n-1) * n
}
func main() {

   // declaring the variables to store the value of n, r and answer
   var n, r, nFactorial, rFactorial, nminusrFactorial, answer int
   fmt.Println("Program to find the nCr using the separate function to find the factorial of n, r and, n-r.")

   // initializing the value of n
   n = 10

   // initializing the value of r
   r = 8

   // finding factorial of n
   nFactorial = factorial(n)

   // finding factorial of r
   rFactorial = factorial(r)

   // finding factorial of n - r 
   nminusrFactorial = factorial(n - r)

   // finding answer by using the formulae
   answer = nFactorial / (rFactorial * nminusrFactorial)

   // printing the result
   fmt.Println("The value of nCr with n =", n, "and r=", r, "is", answer)
} 

输出

Program to find the nCr using the separate function to find the factorial of n, r and, n-r.
The value of nCr with n = 10 and r= 8 is 45

结语

以上是在Golang编程语言中执行nCr(r-combinations)的两种方法。第二种方法在模块化和代码重用性方面要好得多，因为我们可以在项目的任何地方调用该函数。