题解 | #牛牛学数列3#
牛牛学数列3
https://www.nowcoder.com/practice/f65c726d081c4160a9356eabf0dc21d9
#include <stdio.h>
int main() {
int n;
double sum1=0;
int sum2=0;
scanf("%d",&n);
int flag=1;
for(int i=1;i<=n;i++)
{
sum2=sum2+flag*(2*i-1);
sum1=sum1+(1.0/sum2);
flag=-flag;
}
printf("%.3lf",sum1);
return 0;
}
