习题2-4 求交错序列前N项和

#include<stdio.h>
int main()
{
    int i, n, flag;    
    double sum, item;
    
    scanf("%d", &n);
    sum=0;
    flag=1;
    for(i=1; i<=n; i++){
        item = flag*1.0*i/(2*i-1);
        flag = -flag;
        sum = sum+item;
    }
    printf("%.3f", sum);
    
    return 0;
}

标签：int,double,sum,flag,交错,序列,习题,main
来源： https://www.cnblogs.com/ytmsnzy/p/16587877.html