Advent of code 2023 day 14 fast

@numba.njit
def day14_slide_left(grid):
  for row in grid:
    open = 0
    for x, v in enumerate(row):
      if v == ord('.'):
        pass
      elif v == ord('O'):
        if open < x:
          row[open], row[x] = ord('O'), ord('.')
        open += 1
      else:
        open = x + 1


def day14(s, *, part2=False, num=1_000_000_000):
  grid = np.array([[ord(ch) for ch in line] for line in s.splitlines()], np.uint8)
  grid = np.rot90(grid)  # North is now left.
  grid = np.ascontiguousarray(grid)  # Layout in C-order, for tobytes().

  if not part2:
    day14_slide_left(grid)

  else:
    configs: dict[Any, int] = {}  # hashed_grid -> index.
    period = -1
    index = 0
    while True:
      if period < 0:
        if (prev_index := configs.setdefault(grid.tobytes(), index)) != index:
          period = index - prev_index
          print(f'At {index=}, found cycle with {period=}.')
          index = num - (num - index) % period
      if index == num:
        break
      for _ in range(4):
        day14_slide_left(grid)
        grid = np.rot90(grid, -1)
      index += 1

  return sum(len(grid[0]) - x for _, x in np.argwhere(grid == ord('O')))