class DeadEndFiller(MazeSolveAlgo):
"""
1. Scan the maze in any order, looking for dead ends.
2. Fill in each dead end, and any dead-end passages attached to them.
3. What you will get is a maze with only solution tiles.
4. Use a different solver (ShortestPaths) to build a solution path.
"""
def __init__(self, solver=None):
if not solver:
self.solver = ShortestPaths()
else:
self.solver = solver
def _solve(self):
self.grid[self.start] = self.grid[self.end] = 0
self._fill_dead_ends()
return self._build_solutions()
def _build_solutions(self):
"""Now that all of the dead ends have been cut out, the maze still needs to be solved."""
return self.solver.solve(self.grid, self.start, self.end)
def _fill_dead_ends(self):
"""fill all dead ends in the maze"""
# loop through the maze serpentine, and find dead ends
dead_end = self._find_dead_end()
while dead_end != (-1, -1):
# fill-in and wall-off the dead end
self._fill_dead_end(dead_end)
# from the dead end, travel one cell
ns = self._find_unblocked_neighbors(dead_end)
if len(ns) == 0: break
# look at the next cell, if it is a dead end, restart the loop
if len(ns) == 1:
# continue until you are in a junction cell
if self._is_dead_end(ns[0]):
dead_end = ns[0]
continue
# otherwise, find another dead end in the maze
dead_end = self._find_dead_end()
def _fill_dead_end(self, dead_end):
"""After moving from a dead end, we want to fill in it and all
the walls around it.
"""
r,c = dead_end
self.grid[r, c] = 1
self.grid[r - 1, c] = 1
self.grid[r + 1, c] = 1
self.grid[r, c - 1] = 1
self.grid[r, c + 1] = 1
def _find_dead_end(self):
"""A "dead end" is a cell with only zero or one open neighbors.
The start end end count as open.
"""
for r in range(1, self.grid.height, 2):
for c in range(1, self.grid.width, 2):
if (r, c) in [self.start, self.end]:
continue
if self._is_dead_end((r, c)):
return (r, c)
return (-1, -1)
def _is_dead_end(self, cell):
"""A dead end has zero or one open neighbors."""
ns = self._find_neighbors(cell)
if self.grid[cell] == 1:
return False
elif len(ns) in [0, 1]:
return True
else:
return False
class BlindAlley(MazeSolveAlgo):
"""
1. Scan the maze, identify all fully-connected wall systems.
2. Any wall system that touches the border is not a cul-de-sac, remove it.
3. Determine if remaining wall systems are cul-de-sacs.
4. If so, add a wall segment to turn the cul-de-sac into a dead end.
5. Solve using Dead End Filler.
"""
def __init__(self, fill_type='filler', solver=None):
if not solver:
self.solver = ShortestPaths()
else:
self.solver = solver
if fill_type == 'filler':
self._remove_dead_end = self._dead_end_filler
elif fill_type == 'sealer':
self._remove_dead_end = self._dead_end_sealer
else:
self._remove_dead_end = self._dead_end_filler
def _solve(self):
self._seal_culdesacs()
self._fill_dead_ends()
return self._build_solutions()
def _seal_culdesacs(self):
""" identify and seal off all culdesacs """
# identify all fully-connected wall systems
walls = self._find_wall_systems()
# connect wall systems that are disconnected above
walls = self._reduce_wall_systems(walls)
# remove any wall system that touches the maze boundary
walls = self._remove_border_walls(walls)
for wall in walls:
border = self._find_bordering_cells(wall)
if self._wall_is_culdesac(border):
self._fix_culdesac(border)
def _reduce_wall_systems(self, walls):
""" Reduce a collection of walls in a maze to realize
when two walls are actually connected and should be one.
"""
N = len(walls)
for i in range(N - 1):
if walls[i] is None:
continue
for j in range(i, N):
if walls[j] is None:
continue
if self._walls_are_connected(walls[i], walls[j]):
walls[i] += walls[j]
walls[j] = None
# remove "None" walls
return filter(lambda w: w != None, walls)
def _walls_are_connected(self, wall1, wall2):
""" Figure out if two walls are connected at any point. """
if wall1 is None or wall2 is None:
return False
for cell1 in wall1:
for cell2 in wall2:
if self._is_neighbor(cell1, cell2):
return True
return False
def _build_solutions(self):
""" Now that all of the cul-de-sac have been cut out,
the maze still needs to be solved.
"""
return self.solver.solve(self.grid, self.start, self.end)
def _fix_culdesac(self, border):
""" Destroy the culdesac by blocking off the loop. """
if len(border) > 1:
self.grid[self._midpoint(border[0], border[1])] = 1
def _wall_is_culdesac(self, border):
""" A cul-de-sac is a loop with only one entrance. """
num_entrances = 0
for cell in border:
num_neighbors = len(self._find_unblocked_neighbors(cell))
# if a cell has more than 2 neighbors, one must be a cul-de-sac entrance
if num_neighbors > 2:
num_entrances += 1
# if it has more than one entrance, it's not a cul-de-sac
if num_entrances > 1:
return False
return True
def _find_bordering_cells(self, wall):
""" build a buffer, one cell wide, around the wall """
border = set()
# buffer each wall cell by one, add those buffer cells to a set
for cell in wall:
r,c = cell
for rdiff in range(-1, 2):
for cdiff in range(-1, 2):
border.add((r + rdiff, c + cdiff))
# remove all wall cells from the buffer
border = filter(lambda b: b not in wall, border)
# remove all non-navigable cells from the buffer
border = list(filter(lambda b: b[0] % 2 == 1 and b[1] % 2 == 1, border))
# remove all dead ends within the cul-de-sac
return self._remove_internal_deadends(border)
def _remove_internal_deadends(self, border):
""" Complicated cul-de-Sacs can have internal dead ends.
These seriously complicate the logic and need to be removed.
"""
found = True
while found:
found = False
new_border = border
for cell in border:
if len(self._find_unblocked_neighbors(cell)) < 2:
new_border.remove(cell)
found = True
border = new_border
return border
def _remove_border_walls(self, walls):
""" remove any wall system that touches the maze border """
new_walls = []
for wall in walls:
on_edge = False
for cell in wall:
if self._on_edge(cell):
on_edge = True
break
if not on_edge:
new_walls.append(wall)
return new_walls
def _find_wall_systems(self):
""" A wall system is any continiously-adjacent set of walls. """
walls = []
# loop through each cell in the maze
for r in range(self.grid.shape[0]):
for c in range(self.grid.shape[1]):
# if the cell is a wall
if self.grid[r, c] == 1:
found = False
# determine which wall system it belongs in
for i in range(len(walls)):
if self._has_neighbor((r, c), walls[i]):
found = True
walls[i].append((r, c))
if not found:
walls.append([(r, c)])
return walls
def _is_neighbor(self, cell1, cell2):
""" Determine if one cell is adjacent to another """
r_diff = abs(cell1[0] - cell2[0])
c_diff = abs(cell1[1] - cell2[1])
if r_diff == 0 and c_diff == 1:
return True
elif c_diff == 0 and r_diff == 1:
return True
else:
return False
def _has_neighbor(self, cell, list_cells):
""" Determine if your cell has a neighbor in a list of cells """
for target in list_cells:
if self._is_neighbor(cell, target):
return True
return False
def _fill_dead_ends(self):
""" fill all dead ends in the maze """
# loop through the maze serpentine, and find dead ends
for r in range(1, self.grid.shape[0], 2):
for c in range(1, self.grid.shape[1], 2):
if self._is_dead_end((r, c)):
# fill-in or wall-off the dead end
self._remove_dead_end((r, c))
def _dead_end_filler(self, dead_end):
""" Back away from the dead end until you reach an intersection.
Fill the path as you go.
"""
current = dead_end
ns = self._find_unblocked_neighbors(current)
if len(ns) == 1:
self.grid[current] = 1
self.grid[self._midpoint(ns[0], current)] = 1
def _dead_end_sealer(self, dead_end):
""" Back away from the dead end until you reach an intersection.
Block off the dead end passage.
"""
current = dead_end
ns = self._find_unblocked_neighbors(current)
if len(ns) == 1:
last = current
current = ns[0]
self.grid[self._midpoint(last, current)] = 1
def _is_dead_end(self, cell):
""" A dead end has zero or one open neighbors. """
ns = self._find_unblocked_neighbors(cell)
if self._within_one(cell, self.start) or self._within_one(cell, self.end):
return False
elif self.grid[cell] == 1:
return False
elif len(ns) in [0, 1]:
return True
else:
return False
class DeadEndFiller(MazeSolveAlgo):
"""
1. Scan the maze in any order, looking for dead ends.
2. Fill in each dead end, and any dead-end passages attached to them.
3. What you will get is a maze with only solution tiles.
4. Use a different solver (ShortestPaths) to build a solution path.
"""
def __init__(self, solver=None):
if not solver:
self.solver = ShortestPaths()
else:
self.solver = solver
def _solve(self):
self.grid[self.start] = self.grid[self.end] = 0
self._fill_dead_ends()
return self._build_solutions()
def _build_solutions(self):
"""Now that all of the dead ends have been cut out, the maze still needs to be solved."""
return self.solver.solve(self.grid, self.start, self.end)
def _fill_dead_ends(self):
""" fill all dead ends in the maze """
# loop through the maze serpentine, and find dead ends
dead_end = self._find_dead_end()
while dead_end != (-1, -1):
# fill-in and wall-off the dead end
self._fill_dead_end(dead_end)
# from the dead end, travel one cell
ns = self._find_unblocked_neighbors(dead_end)
if len(ns) == 0: break
# look at the next cell, if it is a dead end, restart the loop
if len(ns) == 1:
# continue until you are in a junction cell
if self._is_dead_end(ns[0]):
dead_end = ns[0]
continue
# otherwise, find another dead end in the maze
dead_end = self._find_dead_end()
def _fill_dead_end(self, dead_end):
"""After moving from a dead end, we want to fill in it and all
the walls around it.
"""
r,c = dead_end
self.grid[r, c] = 1
self.grid[r - 1, c] = 1
self.grid[r + 1, c] = 1
self.grid[r, c - 1] = 1
self.grid[r, c + 1] = 1
def _find_dead_end(self):
"""A "dead end" is a cell with only zero or one open neighbors.
The start end end count as open.
"""
for r in range(1, self.grid.shape[0], 2):
for c in range(1, self.grid.shape[1], 2):
if (r, c) in [self.start, self.end]:
continue
if self._is_dead_end((r, c)):
return (r, c)
return (-1, -1)
def _is_dead_end(self, cell):
"""A dead end has zero or one open neighbors."""
ns = self._find_neighbors(cell)
if self.grid[cell] == 1:
return False
elif len(ns) in [0, 1]:
return True
else:
return False
class BlindAlley(MazeSolveAlgo):
"""
1. Scan the maze, identify all fully-connected wall systems.
2. Any wall system that touches the border is not a cul-de-sac, remove it.
3. Determine if remaining wall systems are cul-de-sacs.
4. If so, add a wall segment to turn the cul-de-sac into a dead end.
5. Solve using Dead End Filler.
"""
def __init__(self, fill_type='filler', solver=None):
if not solver:
self.solver = ShortestPaths()
else:
self.solver = solver
if fill_type == 'sealer':
self._remove_dead_end = SEALER
else:
self._remove_dead_end = FILLER
def _solve(self):
self._seal_culdesacs()
self._fill_dead_ends()
return self._build_solutions()
def _seal_culdesacs(self):
""" identify and seal off all culdesacs """
# identify all fully-connected wall systems
walls = self._find_wall_systems()
# connect wall systems that are disconnected above
walls = self._reduce_wall_systems(walls)
# remove any wall system that touches the maze boundary
walls = self._remove_border_walls(walls)
for wall in walls:
border = self._find_bordering_cells(wall)
if self._wall_is_culdesac(border):
self._fix_culdesac(border)
def _reduce_wall_systems(self, walls):
""" Reduce a collection of walls in a maze to realize
when two walls are actually connected and should be one.
"""
N = len(walls)
for i in range(N - 1):
if walls[i] is None:
continue
for j in range(i, N):
if walls[j] is None:
continue
if self._walls_are_connected(walls[i], walls[j]):
walls[i] += walls[j]
walls[j] = None
# remove "None" walls
return [w for w in walls if w != None]
def _walls_are_connected(self, wall1, wall2):
""" Figure out if two walls are connected at any point. """
if wall1 is None or wall2 is None:
return False
for cell1 in wall1:
for cell2 in wall2:
if self._is_neighbor(cell1, cell2):
return True
return False
def _build_solutions(self):
""" Now that all of the cul-de-sac have been cut out,
the maze still needs to be solved.
"""
return self.solver.solve(self.grid, self.start, self.end)
def _fix_culdesac(self, border):
""" Destroy the culdesac by blocking off the loop. """
if len(border) > 1:
r, c = self._midpoint(border[0], border[1])
self.grid[r, c] = 1
def _wall_is_culdesac(self, border):
""" A cul-de-sac is a loop with only one entrance. """
num_entrances = 0
for cell in border:
num_neighbors = len(self._find_unblocked_neighbors(cell))
# if a cell has more than 2 neighbors, one must be a cul-de-sac entrance
if num_neighbors > 2:
num_entrances += 1
# if it has more than one entrance, it's not a cul-de-sac
if num_entrances > 1:
return False
return True
def _find_bordering_cells(self, wall):
""" build a buffer, one cell wide, around the wall """
border = []
# buffer each wall cell by one, append those buffer cells to a list
for cell in wall:
r, c = cell
for rdiff in range(-1, 2):
for cdiff in range(-1, 2):
border.append((r + rdiff, c + cdiff))
# remove all non-unique cells
border = list(set(border))
# remove all wall cells from the buffer
border = [b for b in border if b not in wall]
# remove all non-navigable cells from the buffer
border = [b for b in border if b[0] % 2 == 1 and b[1] % 2 == 1]
# remove all dead ends within the cul-de-sac
return self._remove_internal_deadends(border)
def _remove_internal_deadends(self, border):
""" Complicated cul-de-Sacs can have internal dead ends.
These seriously complicate the logic and need to be removed.
"""
found = True
while found:
found = False
new_border = border
for cell in border:
if len(self._find_unblocked_neighbors(cell)) < 2:
new_border.remove(cell)
found = True
border = new_border
return border
def _remove_border_walls(self, walls):
""" remove any wall system that touches the maze border """
new_walls = []
for wall in walls:
on_edge = False
for cell in wall:
if self._on_edge(cell):
on_edge = True
break
if not on_edge:
new_walls.append(wall)
return new_walls
def _find_wall_systems(self):
""" A wall system is any continiously-adjacent set of walls. """
walls = []
# loop through each cell in the maze
for r in range(self.grid.shape[0]):
for c in range(self.grid.shape[1]):
# if the cell is a wall
if self.grid[r, c] == 1:
found = False
# determine which wall system it belongs in
for i in range(len(walls)):
if self._has_neighbor((r, c), walls[i]):
found = True
walls[i].append((r, c))
if not found:
walls.append([(r, c)])
return walls
def _is_neighbor(self, cell1, cell2):
""" Determine if one cell is adjacent to another """
r_diff = abs(cell1[0] - cell2[0])
c_diff = abs(cell1[1] - cell2[1])
if r_diff == 0 and c_diff == 1:
return True
elif c_diff == 0 and r_diff == 1:
return True
else:
return False
def _has_neighbor(self, cell, list_cells):
""" Determine if your cell has a neighbor in a list of cells """
for target in list_cells:
if self._is_neighbor(cell, target):
return True
return False
def _fill_dead_ends(self):
""" fill all dead ends in the maze """
# loop through the maze serpentine, and find dead ends
for r in range(1, self.grid.shape[0], 2):
for c in range(1, self.grid.shape[1], 2):
if self._is_dead_end((r, c)):
# fill-in or wall-off the dead end
if self._remove_dead_end == SEALER:
self._dead_end_sealer((r, c))
else:
self._dead_end_filler((r, c))
def _dead_end_filler(self, dead_end):
""" Back away from the dead end until you reach an intersection.
Fill the path as you go.
"""
r, c = dead_end
ns = self._find_unblocked_neighbors((r, c))
if len(ns) == 1:
self.grid[r, c] = 1
r, c = self._midpoint(ns[0], (r, c))
self.grid[r, c] = 1
def _dead_end_sealer(self, dead_end):
""" Back away from the dead end until you reach an intersection.
Block off the dead end passage.
"""
current = dead_end
ns = self._find_unblocked_neighbors(current)
if len(ns) == 1:
last = current
current = ns[0]
r, c = self._midpoint(last, current)
self.grid[r, c] = 1
def _is_dead_end(self, cell):
""" A dead end has zero or one open neighbors. """
ns = self._find_unblocked_neighbors(cell)
if self._within_one(cell, self.start) or self._within_one(cell, self.end):
return False
elif self.grid[cell[0], cell[1]] == True: # TODO: WARNING: Index should be typed for more efficient access
return False
elif len(ns) in [0, 1]:
return True
else:
return False