Permutations in which n people can occupy r seats in a classroom in java

Which n people can occupy r seats in a classroom in Java

Our Aim is to write a Java code to find all the possible permutations in which (n) people can occupy (r) number of seats in a classroom.

Suppose (n) number  students are looking to find (r) seats in a classroom so how will they do it . They will do it with simple formula which is given by 

                                                                n P r  =    n! / (n-r)!


Problem Statement :

In a classroom some of the seats are already occupied by students and only a few seats are available in the classroom. The available seats are assumed as r and n number of students are looking for the seat. We need to find in how many different permutations n number of students can sit on r number of chairs.


  • Input number of students in n
  • Input number of seats in r
  • Use permutation formula { factorial(n) / factorial(n-r) }
  • Print Output
Permutations in Java

Java code

import java.util.*;  

public class Main
      public static void main(String[] args)  

            int n, r, per, fact1, fact2;  

            Scanner sc =  new Scanner(;  

            System.out.println("Enter the Value of n: ");  
            n = sc.nextInt();

            System.out.println("Enter the Value of r: ");
            r = sc.nextInt();  

            fact1 = 1;  

            for (int i = n; i > 1; i=i-1)  
                fact1 = fact1 * i;  //calculating factorial (n!)

            int number;  

            number = n - r;  

            fact2 = 1;  

            for (int i = number; i > 1; i=i-1)  
                fact2 = fact2 * i;  //calculating factorial ((n-r)!)

            per = fact1 / fact2;  //calculating  nPr

            System.out.println(per+" ways");  


Enter number of people: 5
Enter number of seats: 9
Total possible arrangements: 120

For similar question click on given button.