题解 | #牛牛学数列3#

#include <stdio.h>

int main() 
{

int m,n;
float sum,sum1,sum2,sum3,t,p;
sum=sum1=sum2=sum3=0;
scanf("%d",&n);
    for(m=1;m<=n;m++)
    {
        if(m%2==0)
        {   
            t=m/2;

            sum2=4*t-1;
        }
        else {  
                p=(m+1)/2;
                sum1=4*p-3;
                }
                sum3=sum3+sum1-sum2;
                sum1=sum2=0;
        sum=sum+1/sum3;
    }
    printf("%.3f",sum);
    return 0;
}