def test_removing_a_piece(self):
b = Board(4)
b.place(0, 1)
b.remove(0, 1)
assert b.positions[0][1] is False
def test_getting_piece_positions(self):
b = Board(4)
b.place(0, 2)
b.place(1, 1)
piece_positions = b.get_piece_positions()
assert piece_positions == [(0, 2), (1, 1)]
def test_placing_a_piece(self):
b = Board(4)
b.place(0, 1)
assert b.positions[0][1] is True
def test_board_does_not_have_piece(self):
b = Board(4)
assert b.has_piece(0, 1) is False
def test_has_piece(self):
b = Board(4)
b.place(0, 2)
assert b.has_piece(0, 2)
def _build_board(self):
board = Board(self.size)
for position in self.positions:
board.place(*position)
return board
def __init__(self, size):
self.board = Board(size)
class Solver:
def __init__(self, size):
self.board = Board(size)
def solve(self):
self._solutions = []
self._place_in_row(0)
return self._solutions
def _place_in_row(self, row):
if row == self.board.size:
self._add_solution()
else:
self._try_in_row(row)
def _add_solution(self):
piece_positions = self.board.get_piece_positions()
solution = Solution(size=self.board.size, positions=piece_positions)
self._solutions.append(solution)
def _try_in_row(self, row):
for col in range(self.board.size):
if self._is_valid(row, col):
self.board.place(row, col)
self._place_in_row(row + 1)
self.board.remove(row, col)
def _is_valid(self, row, col):
return (self._top_is_clear(row, col) and
self._top_left_is_clear(row, col) and
self._top_right_is_clear(row, col))
def _top_is_clear(self, row, col):
row -= 1
while row >= 0:
if self.board.has_piece(row, col):
return False
row -= 1
return True
def _top_left_is_clear(self, row, col):
row -= 1
col -= 1
while row >= 0 and col >= 0:
if self.board.has_piece(row, col):
return False
row -= 1
col -= 1
return True
def _top_right_is_clear(self, row, col):
row -= 1
col += 1
while row >= 0 and col < self.board.size:
if self.board.has_piece(row, col):
return False
col += 1
row -= 1
return True