排名统计.cpp

有n个人

#include <stdio.h>

long fun(int n);
int fac(int n);

int main(void)
{
    long total;
	int n;

	printf("Enter the numbers of students: ");
	scanf("%d", &n);
	total = fun(n);
	printf("%ld\n", total);
	return 0;
}

long fun(int n)
{
	int k,i,c_nk;
	long sum = 0;
	if (n == 0 || n == 1)
		return 1;
	else 
	{
		for (k = 1; k <= n; k++)
		{	
			c_nk = fac(n) / (fac(k) * fac(n-k));
			i = c_nk * fun(n - k);
			sum = sum + i;	
		}
	}
	return sum;
}

int fac(int n)
{
	int result = 1, i;
	for (i = n; i > 0; i--)
		result *= i;
	return result;
}