蛇形矩阵

import java.util.*;

public class Main {

    public Main() {
    }

    public String getResult(int n) {
        List<List<Integer>> layers = new LinkedList<>();
        for (int i = 0, num = 1; i < n; i++) {            
            List<Integer> layer = new LinkedList<>();
            layer.add(num++);
            layers.add(layer);

            for (int j = layers.size() - 2; j >= 0; j--) {
                layers.get(j).add(num++);
            }
        }
        StringBuilder s = new StringBuilder();
        for (List<Integer> layer : layers) {
            for (int i : layer) {
                s.append(i).append(" ");
            }
            s.append("\n");
        }
        return s.toString();
    }

    public static void main(String[] args) {
        Main solution = new Main();
        Scanner in = new Scanner(System.in);
        while (in.hasNext()) {
            int n = Integer.parseInt(in.next());
            String res = solution.getResult(n);
            System.out.print(res);
        }
    } 
}