C program to calculate the value of nPr?

Permutations, nPr can also be represented as P(n,r) is a mathematical formula to find the number of permutations. The formula of P(n, r) is n! / (n – r)!.

The number of permutations on a set of n elements is given by n! where “!” represents factorial.

Input:n=5;r=4;
Output:120

Explanation

P(5, 4) = 5! / (5-4)! => 120 / 1 = 120
5!=1*2*3*4*5*=120

Example

#include<iostream>
using namespace std;
long int fact(int x) {
   int i, f=1;
   for(i=2; i<=x; i++) {
      f=f*i;
   }
   return f;
}
int main() {
   int n, r;
   long int npr;
   n=5;
   r=4;
   npr=fact(n)/fact(n-r);
   printf("%d",npr);
}