def abminval(board, turn, a, b):
val = 2 # has to be less than owin
# check whose turn it is...
if turn == common.constants.O:
next_ = common.constants.X
else:
next_ = common.constants.O
# Check if the game is already finished or not...
gstat = common.game_status(board)
if gstat == common.constants.O:
val = -1
elif gstat == common.constants.X:
val = 1
elif common.constants.NONE not in board:
val = 0
else:
for i in range(3):
for j in range(3):
cval = common.get_cell(board, i, j)
if cval == common.constants.NONE:
newboard = board[:]
common.set_cell(newboard, i, j, turn)
val = min(val, abmaxval(newboard, next_, a, b))
if val <= a:
return val
b = min(val, b)
return val
def min_value(board, a, b):
""" Returns the minimum value for thr board.
"""
# initialize v = +infinity
v = 1000000
# Check state
result = common.game_status(board)
# Check results
if result == common.constants.X:
return 1
elif result == common.constants.O:
return -1
elif check_tie(board):
return 0
# If game is not finished - check the value of v
for y in range(TICTACTOE_HEIGHT):
for x in range(TICTACTOE_WIDTH):
if common.get_cell(board, y, x) == common.constants.NONE:
new_board = board[:]
common.set_cell(new_board, y, x, common.constants.O)
v = min(v, max_value(new_board, a, b))
# For abprun_tictactoe()
if (a is not None) and (b is not None):
if v <= a:
return v
b = min(b, v)
return v
def is_terminal(self):
status = common.game_status(self.board)
# 1 if X wins, 2 if O wins, 0 else
if is_tie(self.board) or status != 0:
self.outcome = status
return True
else:
return False
def abprun_tictactoe_helper(board, turn, alpha, beta):
result = common.game_status(board)
#common.print_board(board)
#print("\n")
if result == common.constants.O or result == common.constants.X:
return result
if result == common.constants.NONE and isFull(board) == 1:
return result
if turn == common.constants.X:
return max_val_ABPrun(board, alpha, beta)
if turn == common.constants.O:
return min_val_ABPrun(board, alpha, beta)
def min_value(state, turn):
v = 10000
status = common.game_status(state)
if status == common.constants.X:
return 1
elif (common.constants.NONE not in state
and status == common.constants.NONE):
return 0
elif status == common.constants.O:
return -1
for successor in expand(state, turn):
v = min(v, max_value(successor, common.constants.X))
return v
def min_value(board):
v = common.constants.X
result = common.game_status(board)
if ((result == common.constants.X) or (result == common.constants.O)):
return result
elif tie(board):
return common.constants.NONE
else:
for i in range(0, len(board)):
if board[i] == 0:
board[i] = common.constants.O
v = minimum(v, max_value(board))
board[i] = 0
return v
def minmax_tictactoe(board, turn):
result = common.game_status(board)
# terminal state, someone winning
if result == common.constants.X or result == common.constants.O:
return result
# terminal state, tie
if result == common.constants.NONE and boardFull(board):
return result
# otherwise, keep playing
if turn == common.constants.X:
return maxX(board)
if turn == common.constants.O:
return maxO(board)
def abmin_value(state, turn, alpha, beta):
v = 10000
status = common.game_status(state)
if status == common.constants.X:
return 1
if (common.constants.NONE not in state
and status == common.constants.NONE):
return 0
if status == common.constants.O:
return -1
for successor in expand(state, turn):
v = min(v, abmax_value(successor, common.constants.X, alpha, beta))
if v <= alpha:
return v
beta = min(beta, v)
return v
def ab_min_value(board, alpha, beta):
v = common.constants.X
result = common.game_status(board)
if ((result == common.constants.X) or (result == common.constants.O)):
return result
elif tie(board):
return common.constants.NONE
else:
for i in range(0, len(board)):
if board[i] == 0:
board[i] = common.constants.O
v = minimum(v, ab_max_value(board, alpha, beta))
board[i] = 0
if (v == minimum(v, alpha)):
return v
beta = minimum(beta, v)
return v
def minmax_tictactoe(board, turn):
#put your code here:
#it must return common.constants.X(1), common.constants.O(2) or common.constants.NONE(0) for tie.
#use the function common.game_status(board), to evaluate a board
#it returns common.constants.X(1) if X wins, common.constants.O(2) if O wins or common.constants.NONE(0) if tie or game is not finished
#the program will keep track of the number of boards evaluated
#result = common.game_status(board);
result = common.game_status(board)
#common.print_board(board)
# print("\n")
if result == common.constants.O or result == common.constants.X:
return result
if result == common.constants.NONE and isFull(board) == 1:
return result
if turn == common.constants.X:
return max_val(board)
if turn == common.constants.O:
return min_val(board)
def minvalue(board_state):
score = float('inf') #initialize the score
result = common.game_status(board_state)
if result == common.constants.X:
return 1
elif result == common.constants.O:
return -1
elif istie_game(board_state):
# common.print_board(board_state)
return 0
# return common.constants.NONE
else:
for i in range(0, len(board_state)):
if board_state[i] == 0:
board_state[i] = common.constants.O
score = min(score, maxvalue(board_state))
board_state[i] = 0
return score
def abprun_helper(board, turn, alpha, beta):
result = common.game_status(board)
# alpha is worst so far for O
alpha = common.constants.X
# beta is worst so far for X
beta = common.constants.O
# terminal state, someone winning
if result == common.constants.X or result == common.constants.O:
return result
# terminal state, tie
if result == common.constants.NONE and boardFull(board):
return result
# otherwise, keep playing
if turn == common.constants.X:
return maxAbX(board, alpha, beta)
if turn == common.constants.O:
return maxAbO(board, alpha, beta)
def maximizer(board, prune, alpha, beta):
status = common.game_status(board)
if (status != 0) or (is_complete(board) and status == 0):
if status == 2:
return -1
else:
return status
else:
v = float('-inf')
for i in range(9):
if board[i] == 0:
board[i] = 1
v = max(v, minimizer(board, prune, alpha, beta))
board[i] = 0
if prune:
if v >= beta:
return v
alpha = max(alpha, v)
return v
def maxvalue_ab(board_state, a, b):
score = float('-inf') #initialize the score
result = common.game_status(board_state)
if result == common.constants.X:
return 1
elif result == common.constants.O:
return -1
elif istie_game(board_state):
# common.print_board(board_state)
return 0
# return common.constants.NONE
else:
for i in range(0, len(board_state)):
if board_state[i] == 0:
board_state[i] = common.constants.X
score = max(score, minvalue_ab(board_state, a, b))
board_state[i] = 0
if score >= b:
return score
a = max(a, score)
return score
def set_outcome(self):
self.outcome = common.game_status(self.board)