Advent of code 2020 day 15

# Accelerate the computation using numba.  This requires moving from a dict
# to a large array.  It seems slower for small numbers, but is 15x faster
# for the larger runs.

def process(s, num_turns=2020):
  l = np.array(list(map(int, s.split(','))), dtype=np.int32)

  @numba.njit
  def func():
    last_turn = np.full(num_turns, -1, dtype=np.int32)
    prev_turn = 0  # dummy initialization
    for turn in range(1, num_turns + 1):
      if turn <= len(l):
        number = l[turn - 1]
      elif prev_turn < 0:
        number = 0
      else:
        number = last_turn[number] - prev_turn

      prev_turn = last_turn[number]
      last_turn[number] = turn
    return number

  return func()

hh.check_eq(process(puzzle_input, num_turns=30_000_000), 1407)