The nPr termed as permutation. They are useful in finding possible permutation of the number in the sets of numbers. To calculate combinations, we will use the formula nPr = n! / (n – r)! , where n represents the total number of items, and r represents the number of items being chosen at a time.
#include <stdio.h> int fact(int n) { int i; int res = 1; for (i = 2; i <= n; i++) { res = res * i; } return res; } int getnPr(int n, int r) { return fact(n)/fact(n-r); } int main() { int num, r; long nprValue; printf("Enter the value of num = "); scanf("%d",&num); printf("Enter the value of r = "); scanf("%d",&r); nprValue = getnPr(num, r); printf("%d C %d = %ld\n", num, r, nprValue); return 0; }
Output:
Enter the value of num = 10
Enter the value of r = 4
10 P 4 = 5040