I am building a maze solver using the breadth first search algorithm and I keep hitting an error that says UnboundLocalError: local variable 'starting_point' referenced before assignment. However, starting_point is a global variable, and it has already been assigned to something. When I try to use it in my program, it does not work. It worked in the function before it. That function was where I declared the variable to be global. Why does the global variable not work in the function next to it?
import queue
import re
def maze_3():
maze3 = [
'00000S000000000000000000000000000000000000000000000000000000000',
'00000 000000000 ',
'00000 000000000 000000000000000000 000000000000000 00000000',
'000000 00000000 000000 00000',
' 00000000 000000000000 000000000000000000 000000',
'00000000 000000000000000000000000000000 0000 000000',
'000000 000 000000000 000 000000 0000',
'000000 000 000000000 00000000 000000 00',
'00 000 0 0000000000 000 000 0000 00 00 00000 000',
'000000 000000 000000000 000 0000 00000',
'0000000000000000 0000000 0000000 000 00000000000',
'000000 000 0000000 0000 00000000000000 00000000',
'0000000000000000E 0000000',
]
return maze3
def finished_maze(maze, solution=''):
global visited
visited = []
global starting_point
starting_point= ''
for position in range(len(maze)):
if position == 'S':
starting_point = maze[i]
break
j = starting_point
k = 0
position = set()
for move in solution:
if move == 'Up':
k -= 1
elif move == 'Down':
k += 1
elif move == 'Left':
j -= 1
elif move == 'Right':
j += 1
for row in range(len(maze)):
for column in range(len(maze)):
if (maze[row], maze[column]) in position:
print('1 ', end='')
else:
print(column + '', end='')
print()
def is_valid(maze, moves):
a = True
for position in range(len(maze)):
if position == 'S':
starting_point = maze[position]
j = starting_point
k = 0
for move in re.findall('[A-Z][a-z]*', moves):
if move == 'Up':
k -= 1
elif move == 'Down':
k += 1
elif move == 'Left':
j -= 1
elif move == 'Right':
j += 1
if not ((j >= 0 and j < len(maze[0])) and (k >= 0 and k < len(maze[0]))):
return not a
elif maze[k][j] == '0':
return not a
return a
def find_solution(maze, moves):
a = True
for position in range(len(maze)):
if position == 'S':
starting_point = maze[position]
j = starting_point
k = 0
if moves in visited:
return not a
for move in re.findall('[A-Z][a-z]*', moves):
if move == 'Up':
k -= 1
elif move == 'Down':
k += 1
elif move == 'Left':
j -= 1
elif move == 'Right':
j += 1
if maze[k][j] == 'E':
print(moves)
print(finished_maze(maze, moves))
return a
visited += move
return not a
space = queue.Queue()
space.put('')
put = ''
maze = maze_3()
while not find_solution(maze, put):
put = space.get()
for i in ['Up', 'Down', 'Left', 'Right']:
location = put + i
if is_valid(maze, location):
space.put(location)
