题解 | #最大的奇约数#

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 long jishu(long n) {
        long s1 = 0;
        if (n == 1) {
            return s1;
        } else {
            s1 = (1 + n) * (n + 1) / 4;
            return s1;
            
        }
    }
    public static long oushu(long n) {
        long s = 0;
        if(n == 2){
            return 1;
        }
        else if(n == 4){
            return 2;
        }
        else
        {
            if(n%4 == 0)
            {
                s = jishu(n/2-1) + oushu(n/2);
                
            }
            else{
                 s = jishu(n/2) + oushu((n/2)-1);
            }
            return s;
        } 
    }


    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int N = in.nextInt();

        long sum1 = 0;
        long sum2 = 0;
        if(N == 1){
            System.out.println(1);
            return;
        }
        else if(N ==2){
            System.out.println(2);
            return;
        }
        if(N%2 != 0){
            sum1 = jishu(N) + oushu(N-1);
        }
        else{
            sum1 = jishu(N-1) + oushu(N);
        }
        System.out.println(sum1);
    }
}

感觉写的很绕