Grokking 230

class Solution {

    final static int[][] DIRS = {{2, 1}, {-2, -1}, {2, -1}, {-2, 1},
                                 {1, 2}, {-1, -2}, {1, -2}, {-1, 2}};
    final static int OFFSET = 302;

    public int minKnightMoves(int x, int y) {
        boolean[][] visited = new boolean[OFFSET * 2 + 1][OFFSET * 2 + 1];

        Queue<int[]> queue = new LinkedList<>();
        queue.offer(new int[] {0, 0});
        visited[OFFSET][OFFSET] = true;
        int steps = 0;

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

            for (int i = 0; i < qSize; i++) {
                int[] at = queue.poll();
                if (at[0] == x && at[1] == y) {
                    return steps;
                }

                for (int[] dir : DIRS) {
                    int rr = at[0] + dir[0];
                    int cc = at[1] + dir[1];

                    if (!visited[OFFSET + rr][OFFSET + cc]) {
                        visited[OFFSET + rr][OFFSET + cc] = true;
                        queue.offer(new int[] {rr, cc});
                    }
                }
            }
            steps++;
        }

        return 0; // unreachable code
    }
}