"""Sudoku Puzzle, by Al Sweigart al@inventwithpython.com The classic 9x9 number placement puzzle. More info at https://en.wikipedia.org/wiki/Sudoku This code is available at https://nostarch.com/big-book-small-python-programming Tags: large, game, object-oriented, puzzle""" import copy, random, sys # This game requires a sudokupuzzle.txt file that contains the puzzles. # Download it from https://inventwithpython.com/sudokupuzzles.txt # Here's a sample of the content in this file: # ..3.2.6..9..3.5..1..18.64....81.29..7.......8..67.82....26.95..8..2.3..9..5.1.3.. # 2...8.3...6..7..84.3.5..2.9...1.54.8.........4.27.6...3.1..7.4.72..4..6...4.1...3 # ......9.7...42.18....7.5.261..9.4....5.....4....5.7..992.1.8....34.59...5.7...... # .3..5..4...8.1.5..46.....12.7.5.2.8....6.3....4.1.9.3.25.....98..1.2.6...8..6..2. # Set up the constants: EMPTY_SPACE = '.' GRID_LENGTH = 9 BOX_LENGTH = 3 FULL_GRID_SIZE = GRID_LENGTH * GRID_LENGTH class SudokuGrid: def __init__(self, originalSetup): # originalSetup is a string of 81 characters for the puzzle # setup, with numbers and periods (for the blank spaces). # See https://inventwithpython.com/sudokupuzzles.txt self.originalSetup = originalSetup # The state of the sudoku grid is represented by a dictionary # with (x, y) keys and values of the number (as a string) at # that space. self.grid = {} self.resetGrid() # Set the grid state to its original setup. self.moves = [] # Tracks each move for the undo feature. def resetGrid(self): """Reset the state of the grid, tracked by self.grid, to the state in self.originalSetup.""" for x in range(1, GRID_LENGTH + 1): for y in range(1, GRID_LENGTH + 1): self.grid[(x, y)] = EMPTY_SPACE assert len(self.originalSetup) == FULL_GRID_SIZE i = 0 # i goes from 0 to 80 y = 0 # y goes from 0 to 8 while i < FULL_GRID_SIZE: for x in range(GRID_LENGTH): self.grid[(x, y)] = self.originalSetup[i] i += 1 y += 1 def makeMove(self, column, row, number): """Place the number at the column (a letter from A to I) and row (an integer from 1 to 9) on the grid.""" x = 'ABCDEFGHI'.find(column) # Convert this to an integer. y = int(row) - 1 # Check if the move is being made on a "given" number: if self.originalSetup[y * GRID_LENGTH + x] != EMPTY_SPACE: return False self.grid[(x, y)] = number # Place this number on the grid. # We need to store a separate copy of the dictionary object: self.moves.append(copy.copy(self.grid)) return True def undo(self): """Set the current grid state to the previous state in the self.moves list.""" if self.moves == []: return # No states in self.moves, so do nothing. self.moves.pop() # Remove the current state. if self.moves == []: self.resetGrid() else: # set the grid to the last move. self.grid = copy.copy(self.moves[-1]) def display(self): """Display the current state of the grid on the screen.""" print(' A B C D E F G H I') # Display column labels. for y in range(GRID_LENGTH): for x in range(GRID_LENGTH): if x == 0: # Display row label: print(str(y + 1) + ' ', end='') print(self.grid[(x, y)] + ' ', end='') if x == 2 or x == 5: # Display a vertical line: print('| ', end='') print() # Print a newline. if y == 2 or y == 5: # Display a horizontal line: print(' ------+-------+------') def _isCompleteSetOfNumbers(self, numbers): """Return True if numbers contains the digits 1 through 9.""" return sorted(numbers) == list('123456789') def isSolved(self): """Returns True if the current grid is in a solved state.""" # Check each row: for row in range(GRID_LENGTH): rowNumbers = [] for x in range(GRID_LENGTH): number = self.grid[(x, row)] rowNumbers.append(number) if not self._isCompleteSetOfNumbers(rowNumbers): return False # Check each column: for column in range(GRID_LENGTH): columnNumbers = [] for y in range(GRID_LENGTH): number = self.grid[(column, y)] columnNumbers.append(number) if not self._isCompleteSetOfNumbers(columnNumbers): return False # Check each box: for boxx in (0, 3, 6): for boxy in (0, 3, 6): boxNumbers = [] for x in range(BOX_LENGTH): for y in range(BOX_LENGTH): number = self.grid[(boxx + x, boxy + y)] boxNumbers.append(number) if not self._isCompleteSetOfNumbers(boxNumbers): return False return True print('''Sudoku Puzzle, by Al Sweigart al@inventwithpython.com Sudoku is a number placement logic puzzle game. A Sudoku grid is a 9x9 grid of numbers. Try to place numbers in the grid such that every row, column, and 3x3 box has the numbers 1 through 9 once and only once. For example, here is a starting Sudoku grid and its solved form: 5 3 . | . 7 . | . . . 5 3 4 | 6 7 8 | 9 1 2 6 . . | 1 9 5 | . . . 6 7 2 | 1 9 5 | 3 4 8 . 9 8 | . . . | . 6 . 1 9 8 | 3 4 2 | 5 6 7 ------+-------+------ ------+-------+------ 8 . . | . 6 . | . . 3 8 5 9 | 7 6 1 | 4 2 3 4 . . | 8 . 3 | . . 1 --> 4 2 6 | 8 5 3 | 7 9 1 7 . . | . 2 . | . . 6 7 1 3 | 9 2 4 | 8 5 6 ------+-------+------ ------+-------+------ . 6 . | . . . | 2 8 . 9 6 1 | 5 3 7 | 2 8 4 . . . | 4 1 9 | . . 5 2 8 7 | 4 1 9 | 6 3 5 . . . | . 8 . | . 7 9 3 4 5 | 2 8 6 | 1 7 9 ''') input('Press Enter to begin...') # Load the sudokupuzzles.txt file: with open('sudokupuzzles.txt') as puzzleFile: puzzles = puzzleFile.readlines() # Remove the newlines at the end of each puzzle: for i, puzzle in enumerate(puzzles): puzzles[i] = puzzle.strip() grid = SudokuGrid(random.choice(puzzles)) while True: # Main game loop. grid.display() # Check if the puzzle is solved. if grid.isSolved(): print('Congratulations! You solved the puzzle!') print('Thanks for playing!') sys.exit() # Get the player's action: while True: # Keep asking until the player enters a valid action. print() # Print a newline. print('Enter a move, or RESET, NEW, UNDO, ORIGINAL, or QUIT:') print('(For example, a move looks like "B4 9".)') action = input('> ').upper().strip() if len(action) > 0 and action[0] in ('R', 'N', 'U', 'O', 'Q'): # Player entered a valid action. break if len(action.split()) == 2: space, number = action.split() if len(space) != 2: continue column, row = space if column not in list('ABCDEFGHI'): print('There is no column', column) continue if not row.isdecimal() or not (1 <= int(row) <= 9): print('There is no row', row) continue if not (1 <= int(number) <= 9): print('Select a number from 1 to 9, not ', number) continue break # Player entered a valid move. print() # Print a newline. if action.startswith('R'): # Reset the grid: grid.resetGrid() continue if action.startswith('N'): # Get a new puzzle: grid = SudokuGrid(random.choice(puzzles)) continue if action.startswith('U'): # Undo the last move: grid.undo() continue if action.startswith('O'): # View the original numbers: originalGrid = SudokuGrid(grid.originalSetup) print('The original grid looked like this:') originalGrid.display() input('Press Enter to continue...') if action.startswith('Q'): # Quit the game. print('Thanks for playing!') sys.exit() # Handle the move the player selected. if grid.makeMove(column, row, number) == False: print('You cannot overwrite the original grid\'s numbers.') print('Enter ORIGINAL to view the original grid.') input('Press Enter to continue...')