你重新加载mazeList每次调用函数。
所以在solve() 开始时，你又回到了起始条件，你最终会在圈子里跑。
使用关键字参数将mazeList 传递给递归调用，默认为None，并且仅在仍为None 时才加载迷宫：
def solve(x, y, mazeList=None):
if mazeList is None:
mazeList = loadMaze("sample.maze")
并将mazeList 传递给递归调用。
下一个问题是你永远不会返回递归调用；当您从 solve() 中调用 solve() 时，您仍然需要返回其结果：
def solve(x, y, mazeList=None):
if mazeList is None:
mazeList = loadMaze("sample.maze")
if mazeList[y][x] == "E":
return "YOU'VE SOLVED THE MAZE!"
elif mazeList[y][x+1] == " ": #right
mazeList[y][x+1] = ">"
return solve(x+1,y,mazeList)
elif mazeList[y+1][x] == " ": #down
mazeList[y+1][x] = "v"
return solve(x,y+1,mazeList)
elif mazeList[y][x-1] == " ": #left
mazeList[y][x-1] = "<"
return solve(x-1,y,mazeList)
elif mazeList[y-1][x] == " ": #up
mazeList[y-1][x] = "^"
return solve(x,y-1,mazeList)
你仍然会用这种技术把自己画在一个角落里；要递归解决迷宫，您需要尝试所有路径，而不仅仅是一条路径，并为每个递归调用提供一个迷宫的副本，并仅标出一条选择的路径。
您也总是测试 next 单元格，但永远不要考虑下一个单元格可能是目标；你永远不会移动到E，因为那个单元格不等于' '，所以它不是移动候选。
以下版本可以解决你的迷宫：
directions = (
(1, 0, '>'),
(0, 1, 'v'),
(-1, 0, '<'),
(0, -1, '^'),
)
def solve(x, y, mazeList=None):
if mazeList is None:
mazeList = loadMaze("sample.maze")
for dx, dy, char in directions:
nx, ny = x + dx, y + dy
if mazeList[ny][nx] == "E":
return "YOU'VE SOLVED THE MAZE!"
if mazeList[ny][nx] == " ":
new_maze = [m[:] for m in mazeList]
new_maze[ny][nx] = char
result = solve(nx, ny, new_maze)
if result is not None:
return result
分别对每个方向进行测试变得乏味，因此我将其替换为在一系列方向上的循环；每个元组都是 x、y 的变化以及朝那个方向移动时要使用的字符。
演示，打印出已解决的迷宫：
>>> def loadMaze(ignored):
... maze = '''\
... ####################################
... #S# ## ######## # # # # #
... # # # # # # #
... # # ##### ## ###### # ####### # #
... ### # ## ## # # # #### #
... # # # ####### # ### #E#
... ####################################
... '''
... return [list(m) for m in maze.splitlines()]
...
>>> directions = (
... (1, 0, '>'),
... (0, 1, 'v'),
... (-1, 0, '<'),
... (0, -1, '^'),
... )
>>>
>>> def solve(x, y, mazeList=None):
... if mazeList is None:
... mazeList = loadMaze("sample.maze")
... for dx, dy, char in directions:
... nx, ny = x + dx, y + dy
... if mazeList[ny][nx] == "E":
... print '\n'.join([''.join(m) for m in mazeList])
... return "YOU'VE SOLVED THE MAZE!"
... if mazeList[ny][nx] == " ":
... new_maze = [m[:] for m in mazeList]
... new_maze[ny][nx] = char
... result = solve(nx, ny, new_maze)
... if result is not None:
... return result
...
>>> solve(1, 1)
####################################
#S# ## ######## # #^>>>>># ^>># #
#v#^>># ^>>> #^# v>>>>#v>>#
#v>>#v#####^##v######^# ####### #v#
### #v##^>>>##v>>>>>#^# # ####v#
# #v>>># #######v>># ### #E#
####################################
"YOU'VE SOLVED THE MAZE!"