浙大版《C語言程式設計（第3版）》題目集練習2-18

#include<stdio.h>

double fact(int n){
	double sum = 1.0;
    int i;
	for(i=1;i<=n;i++)
	sum = sum * i;
	return sum;
}

int main(){
	int m,n;
	double result;

	scanf("%d%d",&m,&n);
	result = fact(n)/(fact(m)*fact(n-m));
	printf("result = %.f",result);
	return 0;
}