Java Program to Calculate nPr

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In the previous article, we have seen Java Program to Calculate nCr  

In this article we will see how to calculate nPr using Java programming language.

Java Program to Calculate nPr

Before jumping into the program let’s know about nPr.

nPr:

nPr is the probability function which represents permutations.

nPr is the selection of objects from group of objects with caring about order of objects means in case of nPr order of objects matters.

nPr = n!/(n-r)!

Where, selecting r objects from n number of objects.

Let’s see different ways to find future investment value.

Method-1: Java Program to Calculate nPr By Using Static Input Value

Approach:

  • Declare the value of n and r value.
  • Check if n value is greater than r value or not if yes then call findPermutation() method.
  • Else nPr value can not be found out as n value is less than r.
  • Declare a method factorial() to find factorial of a number.
  • Inside findPermutation() method using the formula find nPr value.

Program:

import java.util.*;

class Main
{
    public static void main(String arg[])	
    {
        //Scanner class object created
        Scanner sc=new Scanner(System.in);
        //n value declared
        int n=11;
        //r value declared
        int r=6;
        //checking n is greater than equal to r or not
        if(n>=r)
        {
    		System.out.println("Value of "+n+"p"+r+" : "+ findPermutation(n,r));
        }
        else
        {
        	System.out.println("r value can not be more than n value");
        }
        
    }	
    
    //factorial() method to find factorial of a number
    public static double factorial(double n)
    {
        int i=1;
        double fact=1;
        while(i<=n)
        {
       	   fact=fact*i;
           i++;
 	    }
  	      return fact;
    }

    //findPermutation() method to find permutations i.e. nPr value
     public static double findPermutation(int n, int r)
    {
        //finding nPr value
        double nPr=factorial(n)/factorial(n-r);
        //returning nPr value
        return nPr;
    }
}
Output:
Value of 11p6 : 332640.0

Method-2: Java Program to Calculate nPr By Using User Input Value

Approach:

  • Take input of n and r value.
  • Check if n value is greater than r value or not if yes then call findPermutation() method.
  • Else nPr value can not be found out as n value is less than r.
  • Declare a method factorial() to find factorial of a number.
  • Inside findPermutation() method using the formula find nPr value.

Program:

import java.util.*;

class Main
{
    public static void main(String arg[])    
    {
        //Scanner class object created
        Scanner sc=new Scanner(System.in);
        //taking input of n value
        System.out.println("Enter n value: ");
        int n=sc.nextInt();
        //taking input of r value
        System.out.println("Enter r value: ");
        int r=sc.nextInt();
        //checking n is greater than equal to r or not
        if(n>=r)
        {
    		System.out.println("Value of "+n+"p"+r+" : "+ findPermutation(n,r));
        }
        else
        {
        	System.out.println("r value can not be more than n value");
        }
        
    }	
    
    //factorial() method to find factorial of a number
    public static double factorial(double n)
    {
        int i=1;
        double fact=1;
        while(i<=n)
        {
       	   fact=fact*i;
           i++;
 	    }
  	      return fact;
    }

    //findPermutation() method to find permutations i.e. nPr value
     public static double findPermutation(int n, int r)
    {
        //finding nPr value
        double nPr=factorial(n)/factorial(n-r);
        //returning nPr value
        return nPr;
    }
}
Output:

Enter n value: 
5
Enter r value: 
2
Value of 5p2 : 20.0

Interested in programming and want to excel in it by choosing the short ways. Then, practicing with the available Java Program list is mandatory.

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