Caculation of Combinations(计算组合数C(m,n))

1、question:

C(m,n)=?

2、code:            

#include<iostream>
#include<cstdio>
using namespace std;
int fac(int x)
{
int y=1;
for(int i=1;i<=x;i++)
y=y*i;
return y;
}
int m,n,ans;
int main()
{
scanf("%d%d",&m,&n);
ans=fac(m)/(fac(m-n)*fac(n));
printf("%d",ans);
return 0;
}

3、operational result: