[Level 24]
Title: from top to bottom
困惑了很久，这真是迷宫，from top to bottom。但找出的路径图并没有提供有效信息，需要把像素中的R值用二进制写入文件。注意写入的姿势，前两位数据是PK。
某大神使用BFS算法寻路。
from PIL import Image
img = Image.open('maze.png')
dire = [(0,1),(0,-1),(1,0),(-1,0)]
entrance, exit = (639,0), (1,640)
white = (255,255,255,255)
queue = [exit]
next_p = {}
while queue:
pos = queue.pop(0)
if pos==entrance:
break
for d in dire:
temp=(pos[0]+d[0],pos[1]+d[1])
if temp not in next_p and 0<=temp[0]<img.size[0] and 0<=temp[1]<img.size[1] and img.getpixel(temp)!=white:
next_p[temp] = pos
queue.append(temp)
按顺序取出数据，再按正确的姿势写入文件：
path = []
while pos!=exit:
path.append(img.getpixel(pos)[0])
pos = next_p[pos]
open('maze.zip','wb').write(bytes(path[1::2]))
打开 maze.zip 里的 maze.jpg，涂有lake，[Level 25]
