题解 | #超级圣诞树#

import java.util.Scanner;

// 学渣表示不会，从别人的c++代码转来的，正在努力吸收
public class Main {
    public static void copy(int[][] pic, int[][] orgin, int x, int y) {
        //把小树拷贝到指定坐标，x和y为宽5高3的长方形的左上顶点，不是树尖
        for (int i = y; i < y + 3; i++)
            for (int j = x; j < x + 5; j++)
                pic[i][j] = orgin[i - y][j - x];
    }

    public static void draw(int depth, int x, int y, int[][] pic, int[][] orgin) {
        if (depth == 1)
            copy(pic, orgin, x, y);
        else {
            // 规律：n=depth的大树由三个n=depth-1的次小树组成
            int lenx = 5 * (1 << (depth - 1)) + (1 << (depth - 1)) - 1;
            int leny = 3 * (1 << (depth - 1));
            draw(depth - 1, x + lenx / 4 + 1, y, pic, orgin);            //上面的三角形
            draw(depth - 1, x, y + leny / 2, pic, orgin);                //左下的三角形
            draw(depth - 1, x + lenx / 2 + 1, y + leny / 2, pic, orgin); //右下的三角形
        }
    }

    public static void print(int[][] pic, int lenx, int leny) {
        for (int i = 0; i < leny; i++) {
            for (int j = 0; j < lenx; j++) {
                if (pic[i][j] == 0)
                    System.out.print(" ");
                else
                    System.out.print("*");
            }
            System.out.println();
        }
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[][] orgin = new int[3][5];
        for (int i = 0; i < 3; i++) {//将输入为 1 时的图形存放到数组内
            for (int j = 0; j < 5; j++) {
                if ((i == 0 && j == 2) || (i == 1 && j % 2 == 1) || (i == 2 && j % 2 == 0)) {
                    orgin[i][j] = 1;
                } else {
                    orgin[i][j] = 0;
                }
            }
        }
        //
        int lenx = 5 * (1 << (n - 1)) + (1 << (n - 1)) - 1;
        int leny = 3 * (1 << (n - 1));
        // cout << lenx << " " << leny << endl;
        int[][] pic = new int[leny][lenx];
        //初始化大树
        for (int i = 0; i < leny; i++) {
            for (int j = 0; j < lenx; j++) {
                pic[i][j] = 0;
            }
        }
        draw(n, 0, 0, pic, orgin);
        print(pic, lenx, leny); //画树叶
        //画树干
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < lenx / 2; j++) { //画空格，知道底部的中间
                System.out.print(" ");
            }
            System.out.println("*");
        }
    }
}