230403 사라지는 발판

static int[] dy = { -1, 1, 0, 0 };
static int[] dx = { 0, 0, -1, 1 };
static final int INF = 987654321;

public static int solution(int[][] board, int[] aloc, int[] bloc) {
    return solve(board, aloc[0], aloc[1], bloc[0], bloc[1])[1];
}

public static boolean inRange(int[][] board, int y, int x) {
    return y >= 0 && y < board.length && x >= 0 && x < board[0].length;
}

public static boolean isFinished(int[][] board, int y, int x) {
    for (int i = 0; i < 4; i++) {
        int ny = y + dy[i];
        int nx = x + dx[i];
        if (inRange(board, ny, nx) && board[ny][nx] != 0)
            return false;
    }
    return true;
}

public static int[] solve(int[][] board, int y1, int x1, int y2, int x2) {
    if (isFinished(board, y1, x1))
        return new int[] { 0, 0 };

    if (y1 == y2 && x1 == x2)
        return new int[] { 1, 1 };

    int minTurn = INF;
    int maxTurn = 0;
    int canWin = 0;

    for (int i = 0; i < 4; i++) {
        int ny = y1 + dy[i];
        int nx = x1 + dx[i];
        if (!inRange(board, ny, nx) || board[ny][nx] == 0)
            continue;

        board[y1][x1] = 0;
        int[] result = solve(board, y2, x2, ny, nx);
        board[y2][x2] = 1;

        if (result[0] == 0) {
            canWin = 1;
            minTurn = Math.min(minTurn, result[1]);
        } else if (canWin != 1) {
            maxTurn = Math.max(maxTurn, result[1]);
        }
    }

    int turn = canWin == 1 ? minTurn : maxTurn;

    return new int[] { canWin, turn + 1 };
}

출처:https://school.programmers.co.kr/learn/courses/30/lessons/92345