CS50AI_assignments/minesweeper/minesweeper.py

import itertools
import random


class Minesweeper():
    """
    Minesweeper game representation
    """

    def __init__(self, height=8, width=8, mines=8):

        # Set initial width, height, and number of mines
        self.height = height
        self.width = width
        self.mines = set()

        # Initialize an empty field with no mines
        self.board = []
        for i in range(self.height):
            row = []
            for j in range(self.width):
                row.append(False)
            self.board.append(row)

        # Add mines randomly
        while len(self.mines) != mines:
            i = random.randrange(height)
            j = random.randrange(width)
            if not self.board[i][j]:
                self.mines.add((i, j))
                self.board[i][j] = True

        # At first, player has found no mines
        self.mines_found = set()

    def print(self):
        """
        Prints a text-based representation
        of where mines are located.
        """
        for i in range(self.height):
            print("--" * self.width + "-")
            for j in range(self.width):
                if self.board[i][j]:
                    print("|X", end="")
                else:
                    print("| ", end="")
            print("|")
        print("--" * self.width + "-")

    def is_mine(self, cell):
        i, j = cell
        return self.board[i][j]

    def nearby_mines(self, cell):
        """
        Returns the number of mines that are
        within one row and column of a given cell,
        not including the cell itself.
        """

        # Keep count of nearby mines
        count = 0

        # Loop over all cells within one row and column
        for i in range(cell[0] - 1, cell[0] + 2):
            for j in range(cell[1] - 1, cell[1] + 2):

                # Ignore the cell itself
                if (i, j) == cell:
                    continue

                # Update count if cell in bounds and is mine
                if 0 <= i < self.height and 0 <= j < self.width:
                    if self.board[i][j]:
                        count += 1

        return count

    def won(self):
        """
        Checks if all mines have been flagged.
        """
        return self.mines_found == self.mines


class Sentence():
    """
    Logical statement about a Minesweeper game
    A sentence consists of a set of board cells,
    and a count of the number of those cells which are mines.
    """

    def __init__(self, cells, count):
        self.cells = set(cells)
        self.count = count

    def __eq__(self, other):
        return self.cells == other.cells and self.count == other.count

    def __str__(self):
        return f"{self.cells} = {self.count}"

    def known_mines(self):
        if self.cells.__len__() == self.count:
            return self.cells
        return set()

    def known_safes(self):
        if self.count == 0:
            return self.cells
        return set()

    def mark_mine(self, cell): # Remove cell from set and decrease count by one
        if cell in self.cells:
            self.cells.remove(cell)
            self.count -= 1

    def mark_safe(self, cell): # Remove safe cell from cells set
        if cell in self.cells:
            self.cells.remove(cell)


class MinesweeperAI():
    """
    Minesweeper game player
    """

    def __init__(self, height=8, width=8):

        # Set initial height and width
        self.height = height
        self.width = width

        # Keep track of which cells have been clicked on
        self.moves_made = set()

        # Keep track of cells known to be safe or mines
        self.mines = set()
        self.safes = set()

        # List of sentences about the game known to be true
        self.knowledge = []

    def mark_mine(self, cell):
        """
        Marks a cell as a mine, and updates all knowledge
        to mark that cell as a mine as well.
        """
        self.mines.add(cell)
        for sentence in self.knowledge:
            sentence.mark_mine(cell)

    def mark_safe(self, cell):
        """
        Marks a cell as safe, and updates all knowledge
        to mark that cell as safe as well.
        """
        self.safes.add(cell)
        for sentence in self.knowledge:
            sentence.mark_safe(cell)

    def add_knowledge(self, cell, count):
        """
        Called when the Minesweeper board tells us, for a given
        safe cell, how many neighboring cells have mines in them.

        This function should:
            1) mark the cell as a move that has been made
            2) mark the cell as safe
            3) add a new sentence to the AI's knowledge base
               based on the value of `cell` and `count`
            4) mark any additional cells as safe or as mines
               if it can be concluded based on the AI's knowledge base
            5) add any new sentences to the AI's knowledge base
               if they can be inferred from existing knowledge
        """
        self.moves_made.add(cell) #Store information about the cell
        self.mark_safe(cell)
        surrounding_cells = set()
        for i in range(cell[0]-1 if cell[0] - 1 >= 0 else 0, cell[0]+2 if cell[0] + 2 <= self.width else self.width):
            for j in range(cell[1]-1 if cell[1] - 1 >= 0 else 0, cell[1]+2 if cell[1] + 2 <= self.height else self.height):
                count -= int((i, j) in self.mines)
                if (i, j) not in self.safes.union(self.mines):
                    surrounding_cells.add((i, j))

        new_knowledge = Sentence(surrounding_cells, count)
        if new_knowledge in self.knowledge:
            return
        inferred_knowledge = []
        knowledge_cpy = self.knowledge.copy()
        popped = 0
        for i, sentence in enumerate(knowledge_cpy):
            if sentence.cells == set():
                self.knowledge.pop(i - popped)
                popped += 1
                continue
            if new_knowledge.cells.issubset(sentence.cells):
                new_cells = sentence.cells - new_knowledge.cells
                new_count = sentence.count - new_knowledge.count
                new_sentence = Sentence(new_cells, new_count)
                inferred_knowledge.append(Sentence(new_cells, new_count))

            elif sentence.cells.issubset(new_knowledge.cells):
                new_cells = new_knowledge.cells - sentence.cells
                new_count = new_knowledge.count - sentence.count
                new_sentence = Sentence(new_cells, new_count)
                inferred_knowledge.append(new_sentence)

        for i in inferred_knowledge:
            if i.known_safes() != set():
                for j in i.cells:
                    self.mark_safe(j)
            elif i.known_mines() != set():
                for j in i.cells:
                    self.mark_mine(j)

        for i in self.knowledge:
            cells = i.cells.copy()
            if i.known_safes() != set():
                for j in cells:
                    self.mark_safe(j)
            elif i.known_mines() != set():
                for j in cells:
                    self.mark_mine(j)

        inferred_knowledge.append(new_knowledge)
        for i in inferred_knowledge:
            exists = False
            for j in self.knowledge:
                if i == j:
                    exists = True
            if not exists:
                self.knowledge.append(i)

    def make_safe_move(self):
        available_moves = self.safes - self.moves_made
        for s in self.knowledge:
            available_moves = available_moves.union(s.known_safes())
        if available_moves.__len__() == 0:
            return None
        return available_moves.pop()

    def make_random_move(self):
        unavailable_moves = self.moves_made.union(self.mines)
        available_moves = set()
        for i in range(self.width):
            for j in range(self.height):
                if (i, j) not in unavailable_moves:
                    available_moves.add((i, j))
        if available_moves.__len__() == 0:
            return None
        return available_moves.pop()