def main():
GRID_VALUES = '..3.2.6..9..3.5..1..18.64....81.29..7.......8..67.82....26.95..8..2.3..9..5.1.3..'
GRID_VALUES_HARD = '4.....8.5.3..........7......2.....6.....8.4......1.......6.3.7.5..2.....1.4......'
ROWS = 'ABCDEFGHI'
COLUMNS = '123456789'
BOXES = cross(ROWS, COLUMNS)
ROW_UNITS = [cross(r, COLUMNS) for r in ROWS]
COLUMN_UNITS = [cross(ROWS, c) for c in COLUMNS]
SQUARE_UNITS = [
cross(rs, cs) for rs in (ROWS[:3], ROWS[3:6], ROWS[6:])
for cs in (COLUMNS[:3], COLUMNS[3:6], COLUMNS[6:])
]
UNIT_LIST = ROW_UNITS + COLUMN_UNITS + SQUARE_UNITS
solver = SudokuSolver(BOXES, UNIT_LIST)
board_normal = solver.grid_values(GRID_VALUES)
board_hard = solver.grid_values(GRID_VALUES_HARD)
print("-- Normal: Unsolved --")
print("##############################")
solver.display(solver.grid_values(GRID_VALUES), ROWS, COLUMNS)
# Setting all posibilities on empty spaces
all_choises_board = solver.grid_all_posibilities(GRID_VALUES)
# Constraints propagation https://youtu.be/aSYDBcbvC5Y
print("-- Normal: Solved --")
print("##############################")
solver.display(solver.reduce_puzzle(all_choises_board), ROWS, COLUMNS)
all_choises_board_hard = solver.grid_all_posibilities(GRID_VALUES_HARD)
# Hard Sudoku
print("-- Hard: Unsolved --")
print("##############################")
solver.display(solver.grid_values(GRID_VALUES_HARD), ROWS, COLUMNS)
# Reduce does not work anymore with eleminate and only choise technique
print("-- Hard: Unsolved but reduced --")
print("##############################")
solver.display(solver.reduce_puzzle(all_choises_board_hard), ROWS, COLUMNS)
# Hard using DFS
print("-- Hard: DFS --")
print("##############################")
solver.display(solver.search(all_choises_board_hard), ROWS, COLUMNS)
