解迷题 二维码重构 低维空间二 python

codeplus 7 彩蛋题汇总：

https://blog.csdn.net/weixin_42378324/article/details/106449375

题面：

初始二维码原图：https://github.com/dq116/codeplus-7/blob/master/QRcode.png

思路：将图像分成3*3，把定位块放回原位，枚举剩余方块的排列。

首先这个3*3，水平方向上容易看出来，竖直方向上一是凭感觉猜，而是plot画一下，根据坐标轴能看出来。

或者用程序跑出来，本文中便是这样方法，这张二维码长宽都是84，定位块最上面的线是的坐标是56，刚好2/3.

分成3*3后枚举剩余的6块全排列，调用zxing包，识别二维码。

注意1：如果没有zxing需要先pip一下，且zxing会调用一些java文件，所以系统中应该有java的jre/jdk

pip install zxing

6个方块的全排列有6!=720种可能

由于初始排列设置的问题，正确答案的位置是622，我82年的本子跑了774秒。。。

代码：

from PIL import Image
import numpy as np
import matplotlib.pyplot as plt
from itertools import permutations
import time
import zxing

#把b2放到b1
def change(b1,b2):
    global img2
    for i in range(b1[0],b1[1]):
        begin=b1[2]
        end=b1[3]
        vertical_gap=b2[0]-b1[0]
        horizontal_gap=b2[2]-b1[2]
        for j in range(begin,end):
            img2[i,j,:]=img[i + vertical_gap, j +horizontal_gap, :]
def decode_zxing(filename):
    zx = zxing.BarCodeReader()  # 调用条码读取包
    zxdata = zx.decode(filename)  # 图片解码
    if zxdata and zxdata.parsed:
         print(zxdata.parsed)
         return True
    return False
if __name__ == '__main__':
    path=r'path\QRcode.png'
    img=np.array(Image.open(path))
    m,n,dims=img.shape
    # print(m,n)
    now=255#white
    counter=0
    num=3
    pos_block=0
    for i in range(m):
        if img[i][0][0]==0 and now==255:#white turns to black
            if counter == num:
                pos_block=i
                break
            counter+=1
            now=0
        elif  img[i][0][0]==255 and now==0:#black turns to white
            now=255
    # print(pos_block)
    for i in range(pos_block,m):
        begin=int(n*1/3)
        end=int(n*2/3)
        for j in range(begin,end):
            temp=img[i-pos_block,j-begin,:].copy()
            img[i - pos_block, j - begin, :]=img[i,j,:].copy()
            img[i,j,:]=temp.copy()
        begin=end
        end=n
        for j in range(begin, end):
            temp = img[i - pos_block, j , :].copy()
            img[i - pos_block, j , :] = img[i, j, :].copy()
            img[i, j, :] = temp.copy()
    # plt.imshow(img)
    # plt.show()
    # 两条竖线两条横线
    r1 = int(1 / 3 * m)
    r2 = int(2 / 3 * m)
    c1 = int(1 / 3 * n)
    c2 = int(2 / 3 * n)
    b1 = [0, r1, c1, c2]
    b2 = [r1, r2, 0, c1]
    b3 = [r1, r2, c1, c2]
    b4 = [r1, r2, c2, n]
    b5 = [r2, m, c1, c2]
    b6 = [r2, m, c2, n]
    bs = [b1, b2, b3, b4, b5, b6]
    img2=img.copy()
    #正确的排列
    # i = [5, 0, 4, 3, 1, 2]
    full_permutation=list(permutations([0,1, 2, 3,4,5]))
    counter=0
    a = time.perf_counter()
    for i in full_permutation:
        print(i)
        counter+=1
        for j in range(6):
            change(bs[j],bs[i[j]])
        photo=Image.fromarray(img2)
        save_path=r'path\QRcode2.png'
        photo.save(save_path)
        if decode_zxing(save_path):
            print(counter)
            print("time used:" + str(time.perf_counter()))
            break

复原之后：