题解 | #圣诞树#

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);
        // 注意 hasNext 和 hasNextLine 的区别
        int h = in.nextInt();
        int row = h * 4;
        /**
        i为第几行, treeNums为第几次三行
        高度
        4       1
        8       2
        12      3

        第一层，每过3 (i - 3 * treeNums) == 1  "  *  "
        第二层，每过3 (i - 3 * treeNums) == 2  " * * "
        出现" * * "的层
        2       1
        2 5     2
        2 5 8   3

        每是3的倍数输出第三层 i % 3 == 0 "* * *"    treeNums++

        每层左边需要的空格 (h - treeNums - 1) * 3

        当treeNums等于h时，输出杆子
        最大宽  maxWidth
        6
        12
        18
        左边宽(也就是左边空格数)  maxWidth / 2 - 1
        2   
        5   
        8   
         */

        int treeNums = 0;
        for (int i = 1; i <= row; i++) {
            // 杆子
            if (treeNums == h) {
                int maxWidth = treeNums * 6;
                int leftWidth = maxWidth / 2 - 1;
                for (int j = 0; j < h; j++) {
                    for (int k = 0; k < leftWidth; k++) System.out.print(" ");
                    System.out.println("*");
                }
                break;
            }

            // "  *  "输出
            if (i - 3 * treeNums == 1) {
                // 左边空格
                int leftEmpty = (h - treeNums - 1) * 3;
                for (int j = 0; j < leftEmpty; j++) {
                    System.out.print(" ");
                }

                for (int j = 0; j <= treeNums; j++) {
                    System.out.print("  *   ");
                }
                System.out.println();
            }

            // " * * "输出
            if (i - 3 * treeNums == 2) {
                // 左边空格
                int leftEmpty = (h - treeNums - 1) * 3;
                for (int j = 0; j < leftEmpty; j++) {
                    System.out.print(" ");
                }

                for (int j = 0; j <= treeNums; j++) {
                    System.out.print(" * *  ");
                }
                System.out.println();
            }

            // "* * *"输出
            if (i % 3 == 0) {
                // 左边空格
                int leftEmpty = (h - treeNums - 1) * 3;
                for (int j = 0; j < leftEmpty; j++) {
                    System.out.print(" ");
                }
                
                for (int j = 0; j <= treeNums; j++) {
                    System.out.print("* * * ");
                }
                treeNums++;
                System.out.println();
            }

        }
    }
}