偶数求1/2+1/4+...+1/n奇数1/1+1/3+...+1/n

        Scanner scanner = new Scanner(System.in);
        int num = scanner.nextInt();
        double sum = 0;
        if (num%2!=0) {
            for (int i = 1; i <= num; i=i+2) {
                sum += 1.0/i;
                System.out.print(1+"/"+i+"\t");
                System.out.print(1.0/i+"\t");
                System.out.println("");
            }
        }else {
            for (int i = 2; i <= num; i=i+2) {
                sum += 1.0/i;
                System.out.print(1+"/"+i+"\t");
                System.out.print(1.0/i+"\t");
                System.out.println("");
            }
        }
        System.out.println(sum);