[Trilite] Question about play

Original - php Code <?php /* By: Louis-Philippe Huberdeau lphuberdeau@sympatico.ca */ define( 'FILE_CURRENT_GAME', 'current.txt' ); define( 'X', '1' ); define( 'O', '2' ); // Board class // Contains and store board states class Board { var $board; var $list; var $start; // Constructor function Board( $new = false ) { $this->board = array( false, false, false, false, false, false, false, false, false ); if( $new ) { // New game requested, clear the data file $this->list = array( X => array(), O => array() ); } else { $file = file( FILE_CURRENT_GAME ); // If the file does not contain the right data, exit if( sizeof( $file ) != 3 ) die( "Invalid data file." ); // Get the player who started on the first line $this->start = $file[0]; // Read two lines for( $i = 0; 2 > $i; $i++ ) { // Get the right elements in the file: X|O = [0-8]{0,3} if( preg_match( "/(" . X . "|" . O . ")s*=s*([0-8]{0,3})/i", $file[$i], $parts ) ) { // Kill the script if both rows are the same if( is_array( $parts[1] ) ) die( "User data already exists." ); $this->list[ $parts[1] ] = array(); // For each marker in the file for( $j = 0; strlen( $parts[2] ) > $j; $j++ ) { // Add the marker, if not valid, break execution if( !$this->addMarker( $parts[1], $parts[2][$j] ) ) die( "Tile already in use." ); } } else { // Pattern not found, error in file die( "Bad pattern for user data." ); } } // end for } // end new if } // end constructor // Methods function addMarker( $player, $position ) { // Validate the tile if( $position < 0 || $position > 8 ) return false; // Make sure it is currently empty if( $this->board[ $position ] != 0 ) return false; // Set it as the player's $this->board[ $position ] = $player; // Add an element to the end of the list and if too many remain if( array_push( $this->list[ $player ], $position ) > 3 ) { // Remove the first $old = array_shift( $this->list[ $player ] ); $this->board[ $old ] = false; } return true; } function containsLine( $player ) { $patterns = getPatterns(); // Scan all patterns and see if there is a match foreach( $patterns as $pattern ) { // Check every tile until wrong one is found or end is reached for( $i = 0; 3 > $i && $this->board[ $pattern[$i] ] == $player; $i++ ); // End was reached, there is a line if( $i == 3 ) return true; } // No lines were found return false; } function getLastMove( $player ) { if( !is_array( $this->list[ $player ] ) ) return false; if( ( $position = sizeof( $this->list[ $player ] ) - 1 ) >= 0 ) return false; return $this->list[ $player ][ $position ]; } function getPatterns() { return array( array( 0, 1, 2 ), // rows array( 3, 4, 5 ), array( 6, 7, 8 ), array( 0, 3, 6 ), // columns array( 1, 4, 7 ), array( 2, 5, 8 ), array( 0, 4, 8 ), // diagonals array( 2, 6, 6 ) ); } function isEmpty( $position, $round = 0 ) { $empty = true; // Try each user foreach( $this->list as $playerMoves ) // Look over each position from the given turn for( $i = $round; sizeof( $playerMoves ) > $i && $empty; $i++ ) $empty = $empty && !$this->board[ $playerMoves[ $i ] ]; return $empty; } function writeData() { $data = array(); $file = fopen( FILE_CURRENT_GAME, 'w' ); // Prepare the data $data[] = $this->start; foreach( $this->list as $player=>$value ) { $data[] = $player . " = " . implode( '', $value ); } // Write to file fwrite( $file, implode( "n", $data ) ); fclose( $file ); } } // Create the board. If start is 1, a new board is created $board = new Board( $_GET['start'] == 1 ); // Set the other user's move if( isset( $_GET['lastmove'] ) ) { if( !$board->addMarker( O, $_GET['lastmove'] ) ) die( 'Invalid user input.' ); } // Here starts the real thing // Empty tiles $possibilities = array(); // Tiles the opponent can't win if placed there $safe = array(); // Tiles the opponent can't win if placed there and can eventually make a line (in line and 3rd tile empty) $best = array(); // Try all possibilities for( $i = 0; 9 > $i && empty( $finalDecision ); $i++ ) { // Create a copy to work on $copy = $board; // If the tile is empty if( $copy->addMarker( X, $i ) ) { $possibilities[] = $i; // If it makes a line, it's already won if( $copy->containsLine( X ) ) { $finalDecision = $i; } else { $fine = true; // Test the opponent's possibilities to see if it's not an instant loss for( $j = 0; 9 > $j && $fine; $j++ ) { $copy2 = $copy; $copy2->addMarker( O, $j ); $fine = !$copy2->containsLine( O ); } // If the opponent can't win if( $fine ) { $safe[] = $i; // If in the same row as the ex-last move and line not obstructed $patterns = $board->getPatterns(); // If moves have been made (if not first round) if( $board->getLastMove( X ) ) { // Seek all patterns foreach( $patterns as $pattern ) { $count = 0; $hasEmpty = false; foreach( $pattern as $tile ) { if( $tile == $i || $tile == $board->getLastMove( X ) ) $count++; if( $board->isEmpty( $tile, 1 ) ) $hasEmpty = true; } // If both the last move made (only one that will remain) and // the current tile are part of a same pattern and the remaining // tile will be empty next turn if( $count == 2 && $hasEmpty ) $best[] = $i; } } // End not first time } // End opponent can't win } // End line contained } // End empty marker check } if( sizeof( $best ) > 0 ) { // Select a random good possibility $finalDecision = $safe[ mt_rand( 0, sizeof( $safe ) - 1 ) ]; } elseif( sizeof( $safe ) > 0 ) { // Select a random safe possibility $finalDecision = $safe[ mt_rand( 0, sizeof( $safe ) - 1 ) ]; } else { // This code should never be executed, but better than nothing // to avoid a crash. // Select a random possibility and pray $finalDecision = $possibilities[ mt_rand( 0, sizeof( $possibilities ) - 1 ) ]; } // Output the move echo $finalDecision; // Write the data to file $board->writeData(); ?>

 
<?php
/*
   By:
   Louis-Philippe Huberdeau
   lphuberdeau@sympatico.ca
*/
 
define( 'FILE_CURRENT_GAME', 'current.txt' );
define( 'X', '1' );
define( 'O', '2' );
 
// Board class
// Contains and store board states
class Board
{
    var $board;
    var $list;
    var $start;
    
    // Constructor
    function Board( $new = false )
    {
        $this->board = array( false, false, false,
                              false, false, false,
                              false, false, false );
 
        if( $new )
        {
            // New game requested, clear the data file
            $this->list = array( X => array(), O => array() );
        }
        else
        {
            $file = file( FILE_CURRENT_GAME );
 
            // If the file does not contain the right data, exit
            if( sizeof( $file ) != 3 ) die( "Invalid data file." );
            
            // Get the player who started on the first line
            $this->start = $file[0];
 
            // Read two lines
            for( $i = 0; 2 > $i; $i++ )
            {
                // Get the right elements in the file: X|O = [0-8]{0,3}
                if( preg_match( "/(" . X . "|" . O . ")s*=s*([0-8]{0,3})/i", $file[$i], $parts ) )
                {
                    // Kill the script if both rows are the same
                    if( is_array( $parts[1] ) ) die( "User data already exists." );
 
                    $this->list[ $parts[1] ] = array();
 
                    // For each marker in the file
                    for( $j = 0; strlen( $parts[2] ) > $j; $j++ )
                    {
                        // Add the marker, if not valid, break execution
                        if( !$this->addMarker( $parts[1], $parts[2][$j] ) ) die( "Tile already in use." );
                    }
                }
                else
                {
                    // Pattern not found, error in file
                    die( "Bad pattern for user data." );
                }
            } // end for
        } // end new if
    } // end constructor
 
    // Methods
    function addMarker( $player, $position )
    {
        // Validate the tile
        if( $position < 0 || $position > 8 ) return false;
 
        // Make sure it is currently empty
        if( $this->board[ $position ] != 0 ) return false;
 
        // Set it as the player's
        $this->board[ $position ] = $player;
        
        // Add an element to the end of the list and if too many remain
        if( array_push( $this->list[ $player ], $position ) > 3 )
        {
            // Remove the first
            $old = array_shift( $this->list[ $player ] );
            $this->board[ $old ] = false;
        }
        
        return true;
    }
 
    function containsLine( $player )
    {
        $patterns = getPatterns();
 
        // Scan all patterns and see if there is a match
        foreach( $patterns as $pattern )
        {
            // Check every tile until wrong one is found or end is reached
            for( $i = 0; 3 > $i && $this->board[ $pattern[$i] ] == $player; $i++ );
 
            // End was reached, there is a line
            if( $i == 3 ) return true;
        }
 
        // No lines were found
        return false;
    }
 
    function getLastMove( $player )
    {
        if( !is_array( $this->list[ $player ] ) ) return false;
        if( ( $position = sizeof( $this->list[ $player ] ) - 1 ) >= 0 ) return false;
        
        return $this->list[ $player ][ $position ];
    }
 
    function getPatterns()
    {</