def create_extreme_sudoku(sudoku,
goal=17,
eliminate_randomly=50,
objective=lambda sudoku: sudoku.metric):
assert goal >= 17 # Minimum number for solvable sudokus
assert eliminate_randomly < 64
given_coordinates = sudoku.given_coordinates
solver = SudokuSolver()
# Step 1: Remove n random numbers from the sudoku
coordinates_to_eliminate = random.sample(given_coordinates,
eliminate_randomly)
for x, y in coordinates_to_eliminate:
sudoku[x][y] = 0
# Step 2: Try to optimize sudoku according to the objective function
given_coordinates = sudoku.given_coordinates
dead_numbers = set()
resample = lambda dead_numbers: random.sample(
set(range(1, 10)) - dead_numbers, 1)[0]
while len(given_coordinates) > goal:
current_number_to_remove = resample(dead_numbers)
deltas = {
} # Changes in value for objective function given the removal of coordinates of index i
if len(dead_numbers) == 9:
print("Fail at {} given numbers".format(len(given_coordinates)))
import time
time.sleep(4)
return sudoku
for x, y in given_coordinates:
temp_sudoku = copy.copy(sudoku)
old = objective(temp_sudoku)
temp_sudoku[x][y] = 0
temp_sudoku.update()
new = objective(temp_sudoku)
delta = new - old
deltas[(x, y)] = (delta, sudoku[x][y])
max_delta_indices = list(
reversed(
sorted(zip(range(len(deltas)), list(deltas.values())),
key=lambda x: x[1][0])))
max_delta_indices = list(
filter(
lambda delta_tuple: delta_tuple[1][1] ==
current_number_to_remove, max_delta_indices))
print(current_number_to_remove)
print("Indices", max_delta_indices)
if len(max_delta_indices) == 0:
current_number_to_remove = resample(dead_numbers)
continue
# Iterate through all the values, starting with the max, to see whether deleting the associated given number
# results in a proper sudoku or not
removed_number = False
for max_delta_index, max_delta in max_delta_indices:
if max_delta_index == len(max_delta_indices) - 1:
print("Fail at {} given numbers".format(
len(given_coordinates)))
import time
time.sleep(4)
return sudoku
x_max, y_max = given_coordinates[max_delta_index]
temp_sudoku = copy.copy(sudoku)
temp_sudoku[x][y] = 0
temp_sudoku.update()
if solver.is_proper(temp_sudoku):
print("Eliminating given at ({}, {}), {} numbers left.".format(
x_max, y_max,
len(given_coordinates) - 1))
given_coordinates.pop(max_delta_index)
sudoku[x_max][y_max] = 0
sudoku.update()
print(str(sudoku))
removed_number = True
dead_numbers = set()
break
if not removed_number:
dead_numbers.add(current_number_to_remove)
sudoku.update() # Save changes internally
return sudoku
