# The Iterative Maze Problem

I had posted about a recursive maze solver earlier. This is an iterative solution to that problem.

```maze = [
['S','0','0','0'],
['0','1','0','0'],
['0','1','0','0'],
['0','1','0','G'],
]

class MazeSolver:
def __init__(self, maze, verbose=False):
self.maze = maze
self.nrows = len(maze)
self.ncols = len(maze[0])
self.visited = set([])
self.verbose = verbose
def _invalid(self, loc):
if loc[0] < 0 or loc[1] < 0:
return False
elif loc[0] > self.nrows-1 or loc[1] > self.ncols-1:
return False
elif self.maze[loc[0]][loc[1]] in ['1']:
return False
elif loc in self.visited:
return False
else:
return True
def neighbors(self, loc):
x, y = loc
candidates = [(x-1,y), (x+1,y), (x,y-1), (x,y+1)]
nbhd = list(filter(self._invalid, candidates))
return set(nbhd)
def run(self, loc):
nbhd = self.neighbors(loc)
step = 0
if self.verbose:
print("{}: {} -- {} -- {}".format(step, loc, nbhd, self.visited))
while True:
step += 1
if len(nbhd) > 0:
visit = nbhd.pop()
# you win
if self.maze[visit[0]][visit[1]] == 'G':
if self.verbose:
print("{}: {}".format(step, visit))
break