ttt.rb

require 'io/console'

class TicTacToe
  
  attr_reader :state
  
  def initialize *players
    @players = players
    @state = players.map { Array.new(9) }
    @marks = ['X','O']
  end
  
  def print
    # system 'clear'
    board = Array.new(9,'-')
    @state.each_with_index do |state, player_index|
      state.each_with_index do |cell, i|
        board[i] = @marks[player_index] if cell == 1
      end
    end
    puts board.each_slice(3).map { |row| row.join("|") }.join("\n")
  end
  
  def mark x, y, player_index
    cursor = (y*3) + x
    @state[player_index][cursor] = 1
  end
  
  def full?
    @state.reduce(0) { |acc, s| acc + s.reduce(0) { |tacc, t| tacc + 1 if t == 1 }}
  end
end

class AI
  def self.move state
    index = available_squares(state)[0]
    y = index / 3
    x = index % 3
    return [x, y]
  end
  
  private
  
  def self.available_squares state
    available = (0..8).to_a
    state.each do |_state|
      _state.each_with_index do |s, i|
        available -= [i] if s == 1
      end
    end
    available
  end
end

game = TicTacToe.new "Jordan", "Nitin"
game.mark 1, 0, 0
game.print

5.times do
  ai_move = AI.move game.state
  game.mark ai_move[0], ai_move[1], 1
end

game.print