View Code of Problem 71

int main()
{
	int n;
	scanf("%d",&n);
    double fenzi[2],fenmu[2];
	fenzi[0]=2;
	fenzi[1]=3;
	fenmu[0]=1;
	fenmu[1]=2;
    double result=0;
    int i,j;
    j=0;
    for(i=1;i<=n;i++)
    {
    	if(j==0&&i!=1&&i!=2)
    	{
    		fenzi[0]=fenzi[0]+fenzi[1];
    		fenmu[0]=fenmu[0]+fenmu[1];
		}
		if(j==1&&i!=1&&i!=2)
    	{
    		fenzi[1]=fenzi[0]+fenzi[1];
    		fenmu[1]=fenmu[0]+fenmu[1];
		}
		result=result+fenzi[j]/fenmu[j];
		if(j==0)
		  j=1;
		else if(j==1)
		  j=0;
	}
	printf("%.2f",result);
}