题解 | #超级圣诞树#

大致思路：一个大树由三个次小树组成，分别在上、左下、右下三个位置，所以递归绘制即可，具体细节标在注释里了。这个和Repeater这道题有点像。

#include <iostream>
#include <cstdio>
#include <vector>

using namespace std;

void copy(vector<vector<bool>> &pic, vector<vector<bool>> orgin, int x, int y);
void draw(int depth, int x, int y, vector<vector<bool>> &pic, vector<vector<bool>> orgin);
void Print(vector<vector<bool>> pic, int lenx, int leny);

int main()
{
    int n;
    vector<vector<bool>> orgin;
    //初始化原始小树
    orgin.resize(3);
    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].push_back(1);
            else
                orgin[i].push_back(0);
        }

    while (cin >> n)
    {
        int lenx = 5 * (1 << (n - 1)) + (1 << (n - 1)) - 1;
        int leny = 3 * (1 << (n - 1));
        // cout << lenx << " " << leny << endl;
        vector<vector<bool>> pic;
        //初始化大树
        pic.resize(leny);
        for (int i = 0; i < leny; i++)
            for (int j = 0; j < lenx; j++)
                pic[i].push_back(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
                cout << " ";
            cout << "*" << endl;
        }
    }
}

void copy(vector<vector<bool>> &pic, vector<vector<bool>> 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];
}

void draw(int depth, int x, int y, vector<vector<bool>> &pic, vector<vector<bool>> 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
    }
}

void Print(vector<vector<bool>> pic, int lenx, int leny)
{
    for (int i = 0; i < leny; i++)
    {
        for (int j = 0; j < lenx; j++)
        {
            if (pic[i][j] == 0)
                cout << " ";
            else
                cout << "*";
        }
        cout << endl;
    }
}