Can u pls write a java or c++ program to find permutations and combinations recursively

Question

Pls also explain the logic of that program
In this program we will take n and r as input from the user.

Answer 1

//nPr = n! / (n-r)!
//nCr = n! / (r! * (n-r)!)
import java.util.Scanner;
public class nPr
{
/*****************logic for nPr****************/
int value;
int nPr_calculate(int n,int r)
{
if(n>=r && r>0)
{
value = 1;
while(r>=1)
{
value = value*n;
n--;r--;
}
}
else if(n>0 && r==0)
{
value = 1;
while(n!=1)
{
value *= n;
n--;
}
}
return value;
}
}
/**********************************************/

/*****************logic for nCr****************/
public class nCr
{
int value, r_fact;
int nCr_calculate(int n,int r)
{
if(n>=r && r>0)
{
value = r_fact= 1;
while(r>=1)
{
value = value*n;
r_fact = r_fact*r;
n--;r--;
}
value = value/r_fact;
}
else if(n>0 && r==0)
{value = 1;}
return value;
}
/**********************************************/
}
class calculate
{
public static void main(String args[])
{
Scanner sc = new Scanner(System.in);
nPr objP = new nPr();
nCr objC = new nCr();
int result=0;
int n, r;

System.out.println("Input Any Number For \"n\" : ");
n=sc.nextInt();
System.out.println("Input Any Number For \"r\" : ");
r=sc.nextInt();

result = objP.nPr_calculate(n,r);
System.out.println(n + " P " + r + " = "+ result);

result = objC.nCr_calculate(n,r);
System.out.println(n + " C " + r + " = "+ result);
}
}