def eval(player, cols, board):
#print player, cols
#r4.printBoard(cols, board)
count = 0
opp = opponent(player)
for x in range(cols):
y = r4.findMinRow(x, cols, board)
if y*cols >= len(board):
continue
board[y*cols + x] = player
length = r4.findLength(x, y, cols, board)
if length >= 4:
count += 1
elif (y+1)*cols < len(board):
board[(y+1)*cols + x] = opp
length = r4.findLength(x, y+1, cols, board)
if length >= 4:
count -= 1
board[(y+1)*cols + x] = 0
board[y*cols + x] = opp
length = r4.findLength(x, y, cols, board)
if length >= 4:
count -= 1
elif (y+1)*cols < len(board):
board[(y+1)*cols + x] = player
length = r4.findLength(x, y, cols, board)
if length >= 4:
count += 1
board[(y+1)*cols + x] = 0
board[y*cols + x] = 0
return count
def abminimax(player, cols, board, recur, alpha, beta, dict):
#print board
opp = opponent(player)
winner = r4.findWinner(cols, board)
xlen = cols
ylen = len(board)/cols
if winner == player:
return eval_max+recur, -1
elif winner == opp:
return eval_min-recur, -1
if recur == 0:
return eval(player, cols, board), -1
b_hash = hashBoard(board)
# I should be using a better check than this... ie a full comparision
# after the hash comparison
if b_hash in dict:
#score, b_hash_str = dict[b_hash]
#if b_hash_str == str(board):
#print "skip! to %i" % dict[b_hash]
# return score, -1
#else:
# print "false alarm :("
return dict[b_hash], -1
best_move = -1
valid_moves = []
moves = range(xlen)
random.shuffle(moves)
for x in moves: #range(xlen):
y = r4.findMinRow(x, cols, board)
if r4.isValid(x, y, cols, board):
valid_moves.append(x)
else:
continue
board[y*cols + x] = player
score, bluh = abminimax(opp, cols, board, recur - 1,
-beta, -alpha, dict)
board[y*cols + x] = 0
if score < beta:
beta = score
best_move = x
if beta <= alpha:
#print "ab pruning, returning %s" % str((beta, recur, best_move))
dict[b_hash] = -beta #, str(board)
return -beta, best_move
# if there are no valid moves
if len(valid_moves) == 0:
beta = min(beta, 0)
# if you are going to lose...
elif best_move == -1:
# this is a random move, because moves was shuffled
best_move = valid_moves[0]
dict[b_hash] = -beta #, str(board)
return -beta, best_move