题解 | #尼科彻斯定理#

//hj76
//奇数和偶数表达方式略微不同, 本来想奇数偶数合并觉得太麻烦索性就分开写了
//先把中间的两个数找到, 再向两边延申, 注意数组下标是2n和2n+1, 需要延申n/2次

import java.util.Arrays;
import java.util.Scanner;

public class Main
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int []arr = new int[n];
        int k = n*n;
        int a,b;
        if(n%2==0)//偶数
        {
            a=k-1;
            b=k+1;
            for (int i = 0; i < n/2; i++)
            {
                arr[2*i] = a;
                arr[2*i+1] = b;
                a-=2;
                b+=2;
            }
        }
        else//奇数  5   5/2=2
        {
            a= k-2;
            b= k+2;
            arr[n-1] = k;
            for (int i = 0; i < n/2; i++)
            {
                arr[2*i] = a;
                arr[2*i+1] = b;
                a-=2;
                b+=2;
            }
        }

        Arrays.sort(arr);
        String str = "";
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < n; i++)
        {
            sb.append(arr[i]).append("+");
        }
        sb.deleteCharAt(sb.length()-1);
        System.out.println(sb.toString());
    }
}