题解 | #蛇形矩阵#

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(
            new InputStreamReader(System.in));
        String line = reader.readLine();
        int num = Integer.parseInt(line);
        System.out.println(snakeMatrix(num));
    }

    public static String snakeMatrix(int n) {
        int[][] matrix = new int[n][n];
        int snake = 0;
        for (int i = 0; i < n; ++i) {
            for (int x = i, y = 0; x >= 0 && y <= i; --x, ++y) {
                matrix[x][y] = ++snake;
            }
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < n; ++j) {
                if (matrix[i][j] != 0) {
                    sb.append(matrix[i][j]).append(" ");
                }
            }
            sb.append("\n");
        }
        return sb.substring(0, sb.length() - 1);
    }
}