C Program to calculate Permutation and Combination

Write a C Program to calculate Permutation and Combination

Program:

#include<stdio.h>
long permutation(int n, int r);
long combination(int n, int r);
long factorial(int num);


int main(void)
{   
    int n, r;
   
    printf("Enter n: ");
    scanf("%d", &n);
   
    printf("Enter r: ");
    scanf("%d", &r);
   
    printf("Permutation = %ld\n", permutation(n, r));   
    printf("Combination = %ld", combination(n, r));
   
    return 0;
}


long permutation(int n, int r)
{
    return factorial(n) / factorial(n-r);
}

long combination(int n, int r)
{
    return permutation(n, r) / factorial(r);
}

long factorial(int num)
{
    long long fact = 1;
   
    while(num > 0)
    {
        fact *= num;
        num--;
    }
   
    return fact;
}

Output:

Enter n: 10
Enter r: 5
Permutation = 30240
Combination = 252
--------------------------------
Process exited after 8.387 seconds with return value 0
Press any key to continue . . .