组合数.cpp

Visual C++的课件和一些习题及答案

#include<iostream.h>
unsigned long int f (unsigned long int n)
{
	if (n==0||n==1) return (1);
	return n*f(n-1);
}
int g(int m,int r)
{
	if (r>m) cout<<"Input Error"<<endl;
	return f(m)/(f(r)*f(m-r));
}
void main ()
{
	int m,r;
	cin>>m>>r;
	cout<<g(m,r)<<endl;
}