题解 | 尼科彻斯定理

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
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 in = new Scanner(System.in);
        int n = in.nextInt();
        int middle1 = n * n % 2;
        int middle = n * n;
        int length = n / 2;
        int right = 0;
        int left = 0;
        if (middle1 == 0) {
            right = middle + 1;
            left = middle - 1 - (length-1) * 2;
        }else{
            right=middle+2;
            left=middle-length*2;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < length; i++) {
            sb.append((left + 2 * i) + "+");
        }
        if (middle1 == 1) {
            sb.append(middle + "+");
        }
        for (int i = 0; i < length; i++) {
            if (i == length - 1) {
                sb.append(right + 2 * i);
            } else {
                sb.append((right + 2 * i) + "+");
            }
        }
        System.out.println(sb.toString());

    }
}