第1回オフラインリアルタイムどう書くJavaでの解答

package tictactoe;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    //反則だったり、どちらかが勝ったらtrueを返す。
    private static String finished(int[] stage, int i, int pos) {
        if(!isRegal(stage, pos)) {
            return String.format("Foul : %s won.", (i % 2 == 1)?"o": "x");
        } else {
            stage[pos] = (i % 2 == 0)? 1 : 2;
            if(isFill(stage, pos)) {
                return String.format("%s won.", (i % 2 == 0)? "o" : "x");
            }
        }
        return null;
    }
    private static boolean isFill(int[] stage, int pos) {
        int v = stage[pos];
        int x = pos % 3;
        int y = pos / 3;
        boolean a = (stage[position((x + 1) % 3, y)] == v && stage[position((x + 2) % 3, y)] == v) ||
                    (stage[position(x, (y + 1) % 3)] == v && stage[position(x, (y + 2) % 3)] == v);
        boolean b = (stage[0] == stage[4] && stage[4] == stage[8] && stage[4] != 0) ||
                    (stage[2] == stage[4] && stage[4] == stage[6] && stage[4] != 0);
        return a || b;
    }
    private static int position(int x, int y) {
        return x + y * 3;
    }
    private static boolean isRegal(int[] stage, int pos) {
        return stage[pos] == 0;
    }
    private static String game(String inp) {
        // ○: 1, ×: 2
        int[] stage = new int[9];
        char[] chs = inp.toCharArray();
        String msg = null;
        for(int i = 0; i < 9; i++) {
            if((msg = finished(stage, i, (int)(chs[i] - '0')-1)) != null) return msg;
        }
        return "Draw game.";
    }
    public static void main(String[] args) {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        try {
            String line = null;
            while ((line = br.readLine()) != null) {
                String[] a = line.split("\\t");
                if(game(a[1]).equals(a[2])) {
                    System.out.println(a[0] + ":" + game(a[1]));
                } else {
                    System.out.println(a[0] + ":" + a[1]);
                    System.out.println("actual  :\"" + game(a[1]) +"\"");
                    System.out.println("expected:\"" + a[2] +"\"");
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

1   79538246    x won.
2   35497162193 x won.
3   61978543    x won.
4   254961323121    x won.
5   6134278187  x won.
6   4319581 Foul : x won.
7   9625663381  Foul : x won.
8   7975662 Foul : x won.
9   2368799597  Foul : x won.
10  18652368566 Foul : x won.
11  965715  o won.
12  38745796    o won.
13  371929  o won.
14  758698769   o won.
15  42683953    o won.
16  618843927   Foul : o won.
17  36535224    Foul : o won.
18  882973  Foul : o won.
19  653675681   Foul : o won.
20  9729934662  Foul : o won.
21  972651483927    Draw game.
22  5439126787  Draw game.
23  142583697   Draw game.
24  42198637563 Draw game.
25  657391482   Draw game.