[leetcode] problem 934 – shortest bridge

public int (int[][] A) {
    int result = 0;
    int m = A.length;
    int n = A[0].length;
    int[][] directions = new int[][] {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
    Queue<int[]> queue = new LinkedList<>();

    findIsland:
    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
            if (A[i][j] == 1) {
                dfs(queue, A, i, j, m, n);
                break findIsland;
            }
        }
    }

    while (!queue.isEmpty()) {
        int size = queue.size();

        for (int i = 0; i < size; i++) {
            int[] pos = queue.poll();

            for (int[] direction : directions) {
                int x = pos[0] + direction[0];
                int y = pos[1] + direction[1];

                if (x < 0 || y < 0 || x >= m || y >= n || A[x][y] == 2)
                    continue;

                if (A[x][y] == 1)
                    return result;

                A[x][y] = 2;
                queue.offer(new int[] {x, y});
            }
        }

        result++;
    }

    return -1;
}

private void dfs(Queue<int[]> queue, int[][] A, int x, int y, int m, int n) {
    if (x < 0 || y < 0 || x >= m || y >= n || A[x][y] != 1)
        return;

    queue.offer(new int[] {x, y});
    A[x][y] = 2;
    dfs(queue, A, x + 1, y, m, n);
    dfs(queue, A, x - 1, y, m, n);
    dfs(queue, A, x, y + 1, m, n);
    dfs(queue, A, x, y - 1, m, n);
}