View Code of Problem 48

#include<stdio.h>
main()
{
	int i,a=1,b=2,n,temp;
	double sum=0.0;
	scanf("%d",&n);
	sum=b/a;
	for(i=1;i<n;i++)
	{
		temp=b;
		b=a+b;
		a=temp;
		sum+=(double)b/a;//不加（double）就是错的
	}
	printf("%.6lf\n",sum);
}