题解 | #牛牛学数列3#
牛牛学数列3
https://www.nowcoder.com/practice/f65c726d081c4160a9356eabf0dc21d9
import java.util.Scanner; // 注意类名必须为 Main, 不要有任何 package xxx 信息 public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); int n = sc.nextInt(); double sum = 0; for (double i = 1;i<=n;i++){ if((int)i%2==0){ sum -=1/i; }else{ sum +=1/i; } } System.out.printf("%.3f",sum); } }