第一回オフラインリアルタイムどう書く(http://atnd.org/events/30285)
の問題をJavaで解いてみました。
問題のURL(http://nabetani.sakura.ne.jp/hena/1/)
所要時間は、問題を見てから1週間以上、
書き始めてから1時間ほどです。

TickTackToe.java

public class TickTackToe {
    private static final String DRAW_MESSAGE = "Draw game.";
    private enum Player {
        FIRST( "o won.", "Foul : x won.") {
            @Override Player next() { return SECOND; }
        },
        SECOND( "x won.", "Foul : o won." ) {
            @Override Player next() { return FIRST; }
        },
        ;
        Player( String won, String foul ) {
            WON_MESSAGE = won;
            FOUL_MESSAGE = foul;
        }
        private final String WON_MESSAGE;
        private final String FOUL_MESSAGE;
        abstract Player next();
        String won() { return WON_MESSAGE; };
        String foul() { return FOUL_MESSAGE; };
    }

    private static final int BOXES_MAX = 9;
    private static final int[][] LINES = {
        {0, 1, 2},
        {3, 4, 5},
        {6, 7, 8},
        {0, 3, 6},
        {1, 4, 7},
        {2, 5, 8},
        {0, 4, 8},
        {2, 4, 6},
    };

    public String match( String process ) {
        Player[] boxes = new Player[BOXES_MAX];
        Player move = Player.FIRST;
        int indexSize = process.length() < BOXES_MAX
            ? process.length()
            : BOXES_MAX;
        for ( int i = 0; i < indexSize; i++ ) {
            String result = put( process.charAt(i), move, boxes );
            if ( result != null ) {
                return result;
            }
            move = move.next();
        }
        return DRAW_MESSAGE;
    }

    private String put( char place, Player move, Player[] boxes ) {
        int boxesIndex = place - '1';
        if ( boxes[boxesIndex] != null ) {
            return move.foul();
        }
        boxes[boxesIndex] = move;
        for ( int[] line : LINES ) {
            if ( isFullLine( move, line, boxes ) ) {
                return move.won();
            }
        }
        return null;
    }

    private boolean isFullLine( Player move, int[] line, Player[] boxes ) {
        for ( int boxIndex : line ) {
            if ( boxes[boxIndex] != move ) {
                return false;
            }
        }
        return true;
    }
    
    public static void main( String[] args ) {
	if ( args.length == 0 ) {
	    System.out.println( "argument error." );
	    return;
	}
	TickTackToe ttt = new TickTackToe();
	for ( String process : args ) {
	    System.out.println( ttt.match(process) );
	}
    }
}