My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Update day15.py
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2019/day15.py
+40
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2019/day15.py
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from intcode import emulate
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ROBOT_DIRS = [
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Point(1, 0), # north
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Point(-1, 0), # south
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Point(0, -1), # west
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Point(0, 1), # east
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]
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INVERSE_DIRS = {
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0: 1,
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1: 0,
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2: 3,
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3: 2,
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}
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def robot_dfs(vm, graph, curr, approach_d):
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for d in range(4):
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np = curr + ROBOT_DIRS[d]
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if np in graph:
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continue
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# Attempt to move to next tile
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GLOBAL_INPUTS[0] = d + 1
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resp = next(vm)
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if resp == 0:
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BOARD[np] = 0
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else:
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if resp == 2:
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global OXYGEN
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OXYGEN = np
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BOARD[np] = resp
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robot_dfs(vm, graph, np, d)
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# Can't rely on call stack alone to backtrack
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GLOBAL_INPUTS[0] = INVERSE_DIRS[approach_d] + 1
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next(vm)
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def bfs(graph, start, end=None):
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seen = set()
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dist = 0
···
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BOARD = {}
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OXYGEN = None
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ROBOT_DIRS = [
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Point(1, 0), # north
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Point(-1, 0), # south
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Point(0, -1), # west
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Point(0, 1), # east
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]
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# Build up board state by exploration
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vm = emulate(TAPE, 0, GLOBAL_INPUTS)
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try:
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curr = Point(0, 0)
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for _ in range(1000000):
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facing = random.choice(xrange(4))
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while BOARD.get(curr + ROBOT_DIRS[facing], 1) == 0:
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facing = random.choice(xrange(4))
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GLOBAL_INPUTS[0] = facing + 1
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resp = next(vm)
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if resp == 0:
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BOARD[curr + ROBOT_DIRS[facing]] = 0
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elif resp == 1:
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curr += ROBOT_DIRS[facing]
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BOARD[curr] = 1
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elif resp == 2:
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curr += ROBOT_DIRS[facing]
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OXYGEN = curr
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BOARD[curr] = 2
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except StopIteration:
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pass
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# We should have found the oxygen tank after this many ticks
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assert 2 in BOARD.values()
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robot_dfs(vm, BOARD, Point(0, 0), 0)
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print "Optimal movement to oxygen:", bfs(BOARD, Point(0, 0), OXYGEN)
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print "Minutes taken to fill up:", bfs(BOARD, OXYGEN) - 1