[英]Python - backtracking maze generation recursive function understanding
我一直在寻找在python中创建迷宫的方法。
我在rosettacode上遇到了下面的代码。
我知道代码使用递归来构建迷宫。
我了解代码行,知道我在阅读什么,我想使用该代码,但是我缺少对该代码的关键理解。
此代码中的递归函数如何确切知道何时停止?
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))
s = ""
for (a, b) in zip(hor, ver):
s += ''.join(a + ['\n'] + b + ['\n'])
return s
if __name__ == '__main__':
print(make_maze())
将调试打印应用于代码:
from random import shuffle, randrange
def make_maze(w = 3, h =3):
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 debugPrint():
print("-"*16)
s = ""
for (a, b) in zip(hor, ver):
s += ''.join(a + ['\n'] + b + ['\n'])
print(s )
for r in vis:
print(r)
def walk(x, y):
debugPrint()
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))
s = ""
for (a, b) in zip(hor, ver):
s += ''.join(a + ['\n'] + b + ['\n'])
return s
if __name__ == '__main__':
print(make_maze())
可视化正在发生的事情:
----------------
+--+--+--+
| | | |
+--+--+--+
| | | |
+--+--+--+
| | | |
+--+--+--+
[0, 0, 0, 1]
[0, 0, 0, 1]
[0, 0, 0, 1]
[1, 1, 1, 1]
----------------
+--+--+--+
| | | |
+--+--+--+
| | | |
+ +--+--+
| | | |
+--+--+--+
[0, 0, 0, 1]
[1, 0, 0, 1]
[0, 0, 0, 1]
[1, 1, 1, 1]
----------------
+--+--+--+
| | | |
+--+--+--+
| | | |
+ +--+--+
| | |
+--+--+--+
[0, 0, 0, 1]
[1, 0, 0, 1]
[1, 0, 0, 1]
[1, 1, 1, 1]
----------------
+--+--+--+
| | | |
+--+--+--+
| | | |
+ +--+--+
| |
+--+--+--+
[0, 0, 0, 1]
[1, 0, 0, 1]
[1, 1, 0, 1]
[1, 1, 1, 1]
----------------
+--+--+--+
| | | |
+--+--+--+
| | | |
+ +--+ +
| |
+--+--+--+
[0, 0, 0, 1]
[1, 0, 0, 1]
[1, 1, 1, 1]
[1, 1, 1, 1]
----------------
+--+--+--+
| | | |
+--+--+ +
| | | |
+ +--+ +
| |
+--+--+--+
[0, 0, 0, 1]
[1, 0, 1, 1]
[1, 1, 1, 1]
[1, 1, 1, 1]
----------------
+--+--+--+
| | |
+--+--+ +
| | | |
+ +--+ +
| |
+--+--+--+
[0, 0, 1, 1]
[1, 0, 1, 1]
[1, 1, 1, 1]
[1, 1, 1, 1]
----------------
+--+--+--+
| |
+--+--+ +
| | | |
+ +--+ +
| |
+--+--+--+
[0, 1, 1, 1]
[1, 0, 1, 1]
[1, 1, 1, 1]
[1, 1, 1, 1]
----------------
+--+--+--+
| |
+--+ + +
| | | |
+ +--+ +
| |
+--+--+--+
[1, 1, 1, 1]
[1, 0, 1, 1]
[1, 1, 1, 1]
[1, 1, 1, 1]
最终输出:
+--+--+--+
| |
+--+ + +
| | | |
+ +--+ +
| |
+--+--+--+
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