牛牛学数列3
#include<stdio.h>
int main(){
int n,m=0,sign=1;
double sum=0;
scanf("%d",&n);
for(int i=1;i<=2*n-1;i+=2){
m=m+sign*i;
sign*=-1;
sum=sum+1.0/m;
}
printf("%.3lf",sum);
}
int main(){
int n,m=0,sign=1;
double sum=0;
scanf("%d",&n);
for(int i=1;i<=2*n-1;i+=2){
m=m+sign*i;
sign*=-1;
sum=sum+1.0/m;
}
printf("%.3lf",sum);
}
