/* Bai tap 3_2 - Ham tinh to hop chap K cua N */

#include <stdio.h>

unsigned long giaithua(int n)

{

   unsigned long ketqua = 1;

   for (i=2; i<=n; i++)

     ketqua *= i;

   return ketqua;

}

unsigned long to_hop_chap(int k, int n)

{

   return giaithua(n) / (giaithua(k) * giaithua(n-k));

}

void main()

{

  int n, k;

  printf("

Nhap vao gia tri N va K : ");

  scanf("%d%d", &n, &k);

  printf("Top hop chap %d cua %d = %lu", k, n, to_hop_chap(k, n));

  getch();

}