Tic Tac Toe

ttt.php

<?php

function checkwin($board, $pos, $who) {
	$set = '';
	foreach($pos as $pt) {
		$set .= $board[$pt[1]][$pt[0]];
	}
	if($set == str_repeat($who, 3)) return true;
	return false;
}

function boardpos() {
	$pos = array(array(0,0), array(0,1), array(0,2), array(1,0), array(1,1), array(1,2), array(2,0), array(2,1), array(2,2));
	shuffle($pos);
	return $pos;
}

function winboard($board, $who) {
	$win = checkwin($board, array(array(0,0), array(0,1), array(0,2)), $who)
		|| checkwin($board, array(array(1,0), array(1,1), array(1,2)), $who)
		|| checkwin($board, array(array(2,0), array(2,1), array(2,2)), $who)
		|| checkwin($board, array(array(0,0), array(1,1), array(2,2)), $who)
		|| checkwin($board, array(array(2,0), array(1,1), array(0,2)), $who)
		|| checkwin($board, array(array(0,0), array(1,0), array(2,0)), $who)
		|| checkwin($board, array(array(0,1), array(1,1), array(2,1)), $who)
		|| checkwin($board, array(array(0,2), array(1,2), array(2,2)), $who);
	return $win;
}

function willwin($board, $who) {
	$pos = boardpos();
	foreach($pos as $pt) {
		$newboard = $board;
		if($newboard[$pt[1]][$pt[0]] == '_') {
			$newboard[$pt[1]][$pt[0]] = $who;
			if(winboard($newboard, $who)) {
				return $pt;
			}
		}
	}
	return false;
}

function winscore($board, $who) {
	$pos = boardpos();
	$point = false;
	$max = 0;
	foreach($pos as $pt) {
		$score = 0;
		$board2 = $board;
		if($board2[$pt[1]][$pt[0]] == '_') {
			$board2[$pt[1]][$pt[0]] = $who;
			foreach($pos as $pt2) {
				$board3 = $board2;
				if($board3[$pt2[1]][$pt2[0]] == '_') {
					$board3[$pt2[1]][$pt2[0]] = $who;
					if(winboard($board3, $who)) {
						$score++;
					}
				}
			}
			if($score > $max) {
				$max = $score;
				$point = $pt;
			}
		}
	}
	return $point;
}

function sidehas($a, $b, $who) {
	$c = $a . $b;
	if(strpos($c, $who) !== false) {
		if(strpos($c, notplayer($who)) === false) {
			return true;
		}
	}
	return false;
}

function cornerblock($board, $who) {
	$opp = notplayer($who);
	if($board[0][1] == '_' && $board[0][0] == $opp && sidehas($board[2][1], $board[2][2], $opp)) {
		return array(1,0);
	}
	if($board[0][1] == '_' && $board[2][0] == $opp && sidehas($board[0][1], $board[0][2], $opp)) {
		return array(1,0);
	}
	if($board[2][1] == '_' && $board[0][2] == $opp && sidehas($board[2][0], $board[2][1], $opp)) {
		return array(1,2);
	}
	if($board[2][1] == '_' && $board[2][2] == $opp && sidehas($board[0][0], $board[0][1], $opp)) {
		return array(1,2);
	}

	if($board[1][0] == '_' && $board[0][0] == $opp && sidehas($board[1][2], $board[2][2], $opp)) {
		return array(0,1);
	}
	if($board[1][0] == '_' && $board[0][2] == $opp && sidehas($board[1][0], $board[2][0], $opp)) {
		die("b\n");
		return array(0,1);
	}
	if($board[1][2] == '_' && $board[2][0] == $opp && sidehas($board[0][2], $board[1][2], $opp)) {
		return array(2,1);
	}
	if($board[1][2] == '_' && $board[2][2] == $opp && sidehas($board[0][0], $board[1][0], $opp)) {
		return array(2,1);
	}

	if($board[0][0] == '_' && sidehas($board[0][1], $board[0][2], $opp) && sidehas($board[1][0], $board[2][0], $opp)) {
		return array(0,0);
	}
	if($board[2][0] == '_' && sidehas($board[0][0], $board[1][0], $opp) && sidehas($board[2][1], $board[2][2], $opp)) {
		return array(0,2);
	}
	if($board[2][2] == '_' && sidehas($board[0][2], $board[1][2], $opp) && sidehas($board[2][0], $board[2][1], $opp)) {
		return array(2,2);
	}
	if($board[0][2] == '_' && sidehas($board[1][2], $board[2][2], $opp) && sidehas($board[0][0], $board[0][1], $opp)) {
		return array(2,0);
	}
	return false;
}

function allowwin($board, $player) {
	$pos = boardpos();
	foreach($pos as $pt) {
		if($board[$pt[1]][$pt[0]] != '_') continue;
		$newboard = $board;
		$newboard[$pt[1]][$pt[0]] = $player;
		if(willwin($newboard, $player)) {
			return $pt;
		}
	}
	return false;
}

function notplayer($player) {
	return ($player == 'X') ? 'O' : 'X';
}

function displayboard($board, $move = false, $player = '') {
	if($move) {
		$board[$move[1]][$move[0]] = $player;
	}
	foreach($board as $row) {
		echo "$row\n";
	}
}

/* Complete the function below to print 2 integers separated by a single space which will be your next move 
  */
function getnextMove($player, $board){

	$move = false;
	$strategy = 'board full';

	// If a move will win, take it
	if($move = willwin($board, $player)) {
		$strategy = 'to win';
	}
	// If avoiding a move would incure a loss, take it
	else if($move = willwin($board, notplayer($player))) {
		$strategy = 'to block';
	}
	// If there isn't a move in the center square, take it
	elseif($board[1][1] == '_') {
		$strategy = 'to center';
		$move = array(1,1);
	}
	// If a move can block a force, take it
	elseif($move = cornerblock($board, $player)) {
		$strategy = 'to block force';
	}
	// If a move can eventually produce a win, take it
	elseif($move = winscore($board, $player)) {
		$strategy = 'to setup win';
	}

	if($move == false || $board[$move[1]][$move[0]] != '_') {
		// If all else fails, take an empty space
		$moves = array(array(1,1));
		$corners = array(array(0,0),array(2,2),array(0,2),array(2,0));
		shuffle($corners);
		while(count($corners)) {
			$moves[] = array_shift($corners);
		}
		$sides = array(array(1,0),array(0,1),array(1,2),array(2,1));
		shuffle($sides);
		while(count($sides)) {
			$moves[] = array_shift($sides);
		}
		foreach($moves as $pos) {
			if($board[$pos[1]][$pos[0]] == '_') {
				$move = $pos;
				$strategy = 'prefered random';
				break;
			}
		}
	}

	$move[] = $strategy;
	return $move;

}

function playGame($player, $board) {
	$player = ($player == 'C') ? 'X' : 'O';
	$moves = 0;
	displayboard($board);
	while(!winboard($board, 'X') && !winboard($board, 'O') && $moves < 9 && strpos(implode('', $board), '_') !== false) {
		$moves++;
		$move = getnextMove($player, $board);
		if(!$move) {die("'no move'\n");}
		echo "Move $moves, Player $player: " . implode(' ', $move) . "\n";
		$board[$move[1]][$move[0]] = $player;
		displayboard($board);
		$player = notplayer($player);
	}
	if(winboard($board, 'X')) {
		echo "Player X Wins.\n";
		return 'X';
	}
	elseif(winboard($board, 'Y')) {
		echo "Player Y Wins.\n";
		return 'Y';
	}
	else {
		echo "Draw.\n";
		return 'D';
	}
}

/* Complete the function below to print 2 integers separated by a single space which will be your next move 
  */
function nextMove($player, $board){
	if($player == 'C' || $player == 'P') {
		playGame($player, $board);
	}
	elseif($player == 'T') {
		for($z = 1; $z < 1000; $z++) {
			ob_start();
			$outcome = playGame($player, $board);
			$games = ob_get_clean();
			if($outcome != 'D') {
				echo $games;
				die();
			}
		}
		echo "All Draws.\n";
	}
	else {
		$move = array_reverse(array_slice(getnextMove($player, $board), 0, 2));
		echo implode(' ', $move) . "\n";
	}
}

$fp = fopen("php://stdin", "r");

//If player is X, I'm the first player.
//If player is O, I'm the second player.
fscanf($fp, "%s", $player);

//Read the board now. The board is a 3x3 array filled with X, O or _.
$board = array();
for ($i=0; $i<3; $i++) {
	fscanf($fp, "%s", $board[$i]);
}

//$player = 'C';
//$board = ['O_X', '_X_', 'O__'];

nextMove($player,$board);

?>