代码实现:编写一个函数，输入n为偶数时，调用函数求1/2+1/4+...+1/n,当输入n为奇数时，调用函数1/1+1/3+...+1/n

import java.util.Scanner;
//编写一个函数，输入n为偶数时，调用函数求1/2+1/4+...+1/n,当输入n为奇数时，调用函数1/1+1/3+...+1/n
public class Test {
	public static void main(String[] args) {
		int n = getN();
		double sum = 0;
		if (n % 2 == 0) {
			for (int i = 2; i <= n; i = i + 2) {
				sum = sum + 1.0 / i;
			}
		} else {
			for (int i = 1; i <= n; i = i + 2) {
				sum = sum + 1.0 / i;
			}
		}
		System.out.println(sum);
	}
	public static int getN() {
		int n = 0;
		Scanner sc = new Scanner(System.in);
		System.out.println("请输入一个数:");
		while (true) {
			String s = sc.nextLine();
			try {
				n = Integer.parseInt(s);
				break;
			} catch (NumberFormatException e) {
				System.out.println("输入错误,请重新输入:");
			}
		}
		return n;
	}
}