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https://github.com/coding-horror/basic-computer-games.git
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work in progress porting CHECKERS to python
did a first pass, porting the logic, refactoring into functions. Found a few bugs in the original code: - when a computer promoted to a king, the original piece would not be removed from the board - humans could move normal pieces like kings I've noticed at least one bug where the computer does not promote to a king when reaching row 0
This commit is contained in:
Dave LeCompte
358
23 Checkers/python/checkers.py
Normal file
358
23 Checkers/python/checkers.py
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@@ -0,0 +1,358 @@
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"""
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CHECKERS
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How about a nice game of checkers?
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Ported by Dave LeCompte
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"""
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PAGE_WIDTH = 64
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HUMAN_PLAYER = 1
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COMPUTER_PLAYER = -1
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HUMAN_PIECE = 1
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HUMAN_KING = 2
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COMPUTER_PIECE = -1
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COMPUTER_KING = -2
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EMPTY_SPACE = 0
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INVALID_MOVE = -99
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def print_centered(msg):
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spaces = " " * ((PAGE_WIDTH - len(msg)) // 2)
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print(spaces + msg)
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def print_header(title):
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print_centered(title)
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print_centered("CREATIVE COMPUTING MORRISTOWN, NEW JERSEY")
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print()
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print()
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print()
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class Board:
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def __init__(self):
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self.spaces = [[0 for y in range(8)] for x in range(8)]
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for x in range(8):
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if (x % 2) == 0:
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self.spaces[x][6] = COMPUTER_PIECE
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self.spaces[x][2] = HUMAN_PIECE
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self.spaces[x][0] = HUMAN_PIECE
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else:
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self.spaces[x][7] = COMPUTER_PIECE
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self.spaces[x][5] = COMPUTER_PIECE
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self.spaces[x][1] = HUMAN_PIECE
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def __str__(self):
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pieces = {
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EMPTY_SPACE: ".",
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HUMAN_PIECE: "O",
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HUMAN_KING: "O*",
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COMPUTER_PIECE: "X",
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COMPUTER_KING: "X*",
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}
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s = "\n\n\n"
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for y in range(7, -1, -1):
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for x in range(0, 8):
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piece_str = pieces[self.spaces[x][y]]
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piece_str += " " * (5 - len(piece_str))
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s += piece_str
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s += "\n"
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s += "\n\n"
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return s
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def print_instructions():
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print("THIS IS THE GAME OF CHECKERS. THE COMPUTER IS X,")
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print("AND YOU ARE O. THE COMPUTER WILL MOVE FIRST.")
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print("SQUARES ARE REFERRED TO BY A COORDINATE SYSTEM.")
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print("(0,0) IS THE LOWER LEFT CORNER")
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print("(0,7) IS THE UPPER LEFT CORNER")
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print("(7,0) IS THE LOWER RIGHT CORNER")
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print("(7,7) IS THE UPPER RIGHT CORNER")
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print("THE COMPUTER WILL TYPE '+TO' WHEN YOU HAVE ANOTHER")
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print("JUMP. TYPE TWO NEGATIVE NUMBERS IF YOU CANNOT JUMP.")
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print()
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print()
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print()
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def get_spaces():
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for x in range(0, 8):
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for y in range(0, 8):
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yield x, y
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def get_spaces_with_computer_pieces(board):
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for x, y in get_spaces():
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contents = board.spaces[x][y]
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if contents < 0:
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yield x, y
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def get_spaces_with_human_pieces(board):
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for x, y in get_spaces():
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contents = board.spaces[x][y]
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if contents > 0:
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yield x, y
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def pick_computer_move(board):
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r = [INVALID_MOVE] * 5
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for x, y in get_spaces_with_computer_pieces(board):
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contents = board.spaces[x][y]
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if contents == COMPUTER_PIECE:
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for dx in (-1, 1):
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dy = -1
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sub_650(board, x, y, dx, dy, r)
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else:
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for dx in (-1, 1):
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for dy in (-1, 1):
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sub_650(board, x, y, dx, dy, r)
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if r[0] != INVALID_MOVE:
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dx = r[3] - r[1]
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dy = r[4] - r[2]
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if abs(dx) != abs(dy):
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print(r)
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assert abs(dx) == abs(dy)
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return r
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def sub_650(board, x, y, dx, dy, r):
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new_x = x + dx
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new_y = y + dy
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if not ((0 <= new_x <= 7) and (0 <= new_y <= 7)):
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return
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contents = board.spaces[new_x][new_y]
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if contents == 0:
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sub_910(board, x, y, new_x, new_y, r)
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return
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if contents < 0:
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return
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# check landing space
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landing_x = new_x + dx
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landing_y = new_y + dy
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# line 790
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if not ((0 <= landing_x <= 7) and (0 <= landing_y <= 7)):
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return
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if board.spaces[landing_x][landing_y] == 0:
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sub_910(board, x, y, landing_x, landing_y, r)
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def sub_910(board, start_x, start_y, dest_x, dest_y, r):
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q = 0
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if dest_y == 0 and board.spaces[start_x][start_y] == COMPUTER_PIECE:
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q += 2
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if abs(start_y - dest_y) == 2:
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q += 5
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if start_y == 7:
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q -= 2
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if dest_x in (0, 7):
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q += 1
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for c in (-1, 1):
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if (0 <= dest_x + c <= 7) and (1 <= dest_y):
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# line 1035
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if board.spaces[dest_x + c][dest_y - 1] < 0:
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q += 1
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# line 1040
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elif (0 <= dest_x - c <= 7) and (dest_y + 1 <= 7):
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# line 1045
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if (
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(board.spaces[dest_x + c][dest_y - 1] > 0)
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and (board.spaces[dest_x - c][dest_y + 1] == EMPTY_SPACE)
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or ((dest_x - c == start_x) and (dest_y + 1 == start_y))
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):
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q -= 2
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# line 1080
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if q > r[0]:
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r[0] = q
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r[1] = start_x
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r[2] = start_y
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r[3] = dest_x
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r[4] = dest_y
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def remove_r_pieces(board, r):
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remove_pieces(board, r[1], r[2], r[3], r[4])
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def remove_pieces(board, start_x, start_y, dest_x, dest_y):
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board.spaces[dest_x][dest_y] = board.spaces[start_x][start_y]
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board.spaces[start_x][start_y] = EMPTY_SPACE
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if abs(dest_x - start_x) == 2:
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mid_x = (start_x + dest_x) // 2
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mid_y = (start_y + dest_y) // 2
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board.spaces[mid_x][mid_y] = EMPTY_SPACE
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def play_computer_move(board, r):
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print(f"FROM {r[1]} {r[2]} TO {r[3]} {r[4]}")
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while True:
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if r[4] == 0:
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# KING ME
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board.spaces[r[3]][r[4]] = COMPUTER_KING
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remove_r_pieces(board, r)
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return
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else:
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# line 1250
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board.spaces[r[3]][r[4]] = board.spaces[r[1]][r[2]]
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remove_r_pieces(board, r)
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if abs(r[1] - r[3]) != 2:
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return
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# line 1340
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x = r[3]
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y = r[4]
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r[0] = INVALID_MOVE
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if board.spaces[x][y] == COMPUTER_PIECE:
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for a in (-2, 2):
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try_extend(board, r, x, y, a, -2)
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else:
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assert board.spaces[x][y] == COMPUTER_KING
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for a in (-2, 2):
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for b in (-2, 2):
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try_extend(board, r, x, y, a, b)
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if r[0] != INVALID_MOVE:
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print(f"TO {r[3]} {r[4]}")
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else:
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return
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def try_extend(board, r, x, y, a, b):
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# line 1370
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nx = x + a
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ny = y + b
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if not ((0 <= nx <= 7) and (0 <= ny <= 7)):
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return
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if (board.spaces[nx][ny] == EMPTY_SPACE) and (
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board.spaces[nx + a // 2][ny + b // 2] > 0
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):
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sub_910(board, x, y, nx, ny, r)
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def get_human_move(board):
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is_king = False
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while True:
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print("FROM?")
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from_response = input()
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x, y = [int(c) for c in from_response.split(",")]
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if board.spaces[x][y] > 0:
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break
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is_king = board.spaces[x][y] == HUMAN_KING
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while True:
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print("TO?")
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to_response = input()
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a, b = [int(c) for c in to_response.split(",")]
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if (not is_king) and (b < y):
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# CHEATER! Trying to move non-king backwards
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continue
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if (
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(board.spaces[a][b] == 0)
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and (abs(a - x) <= 2)
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and (abs(a - x) == abs(b - y))
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):
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break
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return x, y, a, b
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def get_human_extension(board, sx, sy):
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is_king = board.spaces[sx][sy] == HUMAN_KING
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while True:
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print("+TO?")
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to_response = input()
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a1, b1 = [int(c) for c in to_response.split(",")]
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if a1 < 0:
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return False, None
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if (not is_king) and (b1 < sy):
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# CHEATER! Trying to move non-king backwards
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continue
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if (
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(board.spaces[a1][b1] == EMPTY_SPACE)
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and (abs(a1 - sx) == 2)
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and (abs(b1 - sy) == 2)
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):
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return True, (sx, sy, a1, b1)
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def play_human_move(board, start_x, start_y, dest_x, dest_y):
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remove_pieces(board, start_x, start_y, dest_x, dest_y)
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if dest_y == 7:
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# KING ME
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board.spaces[dest_x][dest_y] = HUMAN_KING
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def print_human_won():
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print()
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print("YOU WIN.")
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def print_computer_won():
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print()
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print("I WIN.")
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def check_pieces(board):
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if len(list(get_spaces_with_computer_pieces(board))) == 0:
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print_human_won()
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return False
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if len(list(get_spaces_with_computer_pieces(board))) == 0:
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print_computer_won()
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return False
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return True
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def play_game():
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board = Board()
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while True:
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r = pick_computer_move(board)
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if r[0] == INVALID_MOVE:
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print_human_won()
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return
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play_computer_move(board, r)
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print(board)
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if not check_pieces(board):
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return
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sx, sy, dx, dy = get_human_move(board)
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play_human_move(board, sx, sy, dx, dy)
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if abs(dx - sx) == 2:
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while True:
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extend, move = get_human_extension(board, dx, dy)
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if not extend:
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break
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sx, sy, dx, dy = move
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play_human_move(board, sx, sy, dx, dy)
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def main():
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print_header("CHECKERS")
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print_instructions()
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play_game()
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if __name__ == "__main__":
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main()
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