mat*_*317 5 python maze depth-first-search
欢迎.有人能解释一下这段代码会发生什么吗？我想知道这是如何工作的(它来自http://rosettacode.org/wiki/Maze_generation#Python).
from random import shuffle, randrange
def make_maze(w = 16, h = 8):
vis = [[0] * w + [1] for _ in range(h)] + [[1] * (w + 1)]
ver = [["| "] * w + ['|'] for _ in range(h)] + [[]]
hor = [["+--"] * w + ['+'] for _ in range(h + 1)]
def walk(x, y):
vis[y][x] = 1
d = [(x - 1, y), (x, y + 1), (x + 1, y), (x, y - 1)]
shuffle(d)
for (xx, yy) in d:
if vis[yy][xx]: continue
if xx == x: hor[max(y, yy)][x] = "+ "
if yy == y: ver[y][max(x, xx)] = " "
walk(xx, yy)
walk(randrange(w), randrange(h))
for (a, b) in zip(hor, ver):
print(''.join(a + ['\n'] + b))
make_maze()
我对迷宫生成一无所知,但我也很好奇这段代码是如何工作的.以下是一些见解:
这两行打印迷宫:
for (a, b) in zip(hor, ver):
print(''.join(a + ['\n'] + b))
如果我们把这些线定义了三条线之后会发生什么vis,ver和hor？我们得到这个:
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
您甚至可以在递归调用之前放置这两行,walk(xx,yy)并查看迷宫演变的一些步骤:
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+ + +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+ + +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+ + +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+ + +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+ + +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+ + + +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+ + +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+ + + +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+ + + +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+ + + +--+--+--+--+--+--+--+--+--+--+--+
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+--+--+ +--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | |
+--+--+ + + +--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+ + + +--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | |
+--+--+ +--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+ +--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | | | | | | | | | | | | | | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
[...]
现在让我们关注一下walk(x,y).正如其名称和打印输出所示,此功能在迷宫中走动,以随机方式移除墙壁以构建路径.
这个电话:
walk(randrange(w), randrange(h))
在迷宫内的随机位置初始化步行.网格中的每个单元格只访问一次; 被访问的单元格被标记为vis.
此行使用当前单元格的所有四个邻居初始化一个数组:
d = [(x - 1, y), (x, y + 1), (x + 1, y), (x, y - 1)]
以随机顺序访问这些(感谢shuffle(d))
这两条线是在建造迷宫路径时移除墙壁的线条:
# remove horizontal wall, "+--" turns into "+ "
if xx == x: hor[max(y, yy)][x] = "+ "
# remove vertical wall, "|" turns into " "
if yy == y: ver[y][max(x, xx)] = " "
关于这个算法还有更多的说法(参见Jongware的评论),但是只要理解这段特殊的代码,这些就是你可以做的事情.