gistfile1.txt

#!/usr/bin/env ruby
board = ARGV[0]
def corner_available?(board)
  [0,2,6,8].each do |num|
    if board[num].chr.to_s == '-'
      return num
    end
  end
end

$ouput_move = false

def return_move(move)
  unless $output_move
    puts move 
  end
  $output_move = true
end

def always_get_valid(board)
  $always_get_valid_called = true
  counter = 0
  board.each_char do |char|
    if char == '-'
      return_move(counter)
      break
    end
    counter += 1
  end
end

def silly_stuff(board)
  begin
    if board[4].chr.to_s == '-'
      return_move 4
    elsif corner_available?(board)
      return_move corner_available?(board)
    else
      always_get_valid(board)
    end
  rescue
    if not($always_get_valid)
      always_get_valid(board)
    end
  end
end

def make_move(board, position)
  new_board = board.dup
  new_board[position] = what_player(board)
  new_board
end

def who_has_won(board)
  if board.match /xxx/ or board.match /x..x..x../ or board.match /.x..x..x./ or board.match /..x..x..x/ or board.match /x...x...x/ or board.match /..x.x.x../
    return 'x'
  elsif board.match /000/ or board.match /0..0..0../ or board.match /.0..0..0./ or board.match /..0..0..0/ or board.match /0...0...0/ or board.match /..0.0.0../
    return '0'
  else
    return nil
  end
end

def generate_moves(board)
  output = []
  counter = 0
  board.each_char do |char|
    if char.to_s == '-'
      output << counter
    end
    counter += 1
  end
  return output
end

def count_xs(board)
  board.select {|x| x == 'x'}.length
end
def count_zeroes(board)
  board.select {|x| x == '0'}.length
end

def count_stuff(board, stuff)
  board.select {|x| x == stuff}.length
end

def what_player(board)
  split_board = board.split(//)
  if count_zeroes(split_board) == count_xs(split_board)
    return '0'
  else
    return 'x'
  end
end

$other_lookup = {'x' => '0', '0' => 'x'}

def driver(board)
  current_player = what_player(board)
  $us = current_player
  $other = $other_lookup[$us]
  best_score = 0
  best_move = -1
  generate_moves(board).each do |move|
    new_board = make_move(board, move)
    score = lookahead(new_board, 1000)
    if score > best_score
      best_score = score
      best_move = move
    end
  end
  return best_move
end

def evaluate_end_game(board, limit)
  winner = who_has_won(board)
  if winner == $us
    return 1000 * limit
  else
    return -1000 * limit
  end
end

def lookahead(board, limit)
  if who_has_won(board) == 'x' or who_has_won(board) == '0'
    return evaluate_end_game(board, limit)
  end
  best_score = 0
  current_player = what_player(board)
  generate_moves(board).each do |move|
    new_board = make_move(board, move)
    score = lookahead(new_board, limit-1)
    if score > best_score
      best_score = score
      best_move = move
    end
  end
  return best_score
end

begin
  if board.match /---------/
    return_move 5
  else
    foo = driver(board)
    if foo != -1
      return_move foo
    else
      silly_stuff(board)
    end
  end
rescue
  silly_stuff(board)
end