Eddy's company publishes a kind of lottery.This set of lottery which are numbered 1 to n, and a set of one of each is required for a prize .With one number per lottery, how many lottery on average are required to make a complete set
of n coupons?

Input consists of a sequence of lines each containing a single positive integer n, 1<=n<=22, giving the size of the set of coupons.

For each input line, output the average number of lottery required to collect the complete set of n coupons. If the answer is an integer number, output the number. If the answer is not integer, then output the integer part of the
answer followed by a space and then by the proper fraction in the format shown below. The fractional part should be irreducible. There should be no trailing spaces in any line of ouput.

2
5
17

3 
   5
11 --
   12
   340463
58 ------
   720720

eddy

 

计算方法：

n*(1/1+1/2+1/3+...+1/n)

不过输出非常恶心

要各种注意

还好1Y ^_^

 

 

我的代码：

//n*(1/1+1/2+1/3+...+1/n)
#include<stdio.h>
#include<string.h>

typedef __int64 ll;

ll gcd(ll a,ll b)
{
	if(b==0)
		return a;
	else
		return gcd(b,a%b);
}

ll lcm(ll a,ll b)
{
	return a/gcd(a,b)*b;
}

ll numlen(ll n)
{
	ll l=0;
	while(n)
	{
		n=n/10;
		l++;
	}
	return l;
}

int main()
{
	ll n,son,mother,g,d,i;
	while(scanf("%I64d",&n)!=EOF)
	{
		mother=1,son=0;
		for(i=1;i<=n;i++)
			mother=lcm(mother,i);
		for(i=1;i<=n;i++)
			son=son+mother/i;
		son=son*n;
		g=gcd(mother,son);
		son=son/g;
		mother=mother/g;
		d=son/mother;
		son=son%mother;
		if(son==0)
		{
			printf("%d\n",d);
			continue;
		}
		ll l1=numlen(d);
		ll l2=numlen(mother);
		for(i=0;i<=l1;i++)
			printf(" ");
		printf("%I64d\n",son);
		printf("%I64d ",d);
		for(i=1;i<=l2;i++)
			printf("-");
		printf("\n");
		for(i=0;i<=l1;i++)
			printf(" ");
		printf("%I64d\n",mother);
	}
	return 0;
}