My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add 2022/17
+97
+96
2022/day17.py
+96
2022/day17.py
···
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import fileinput
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from utils import Point, N, S, E, W
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ROCKS = [
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[Point(0, 0), Point(1, 0), Point(2, 0), Point(3, 0)],
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[Point(1, 0), Point(0, 1), Point(1, 1), Point(2, 1), Point(1, 2)],
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[Point(0, 0), Point(1, 0), Point(2, 0), Point(2, 1), Point(2, 2)],
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[Point(0, 0), Point(0, 1), Point(0, 2), Point(0, 3)],
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[Point(0, 0), Point(1, 0), Point(0, 1), Point(1, 1)],
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]
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pattern = fileinput.input()[0].strip()
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lcm = len(pattern) * len(ROCKS)
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def simulate(target_rocks, key_height=10):
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tower_hats = {}
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curr_rock = None
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move_num = 0
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rocks = 0
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height = 0
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bonus_height = 0
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chamber = {Point(x, 0): "#" for x in range(7)}
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while rocks < target_rocks:
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if curr_rock is None:
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# Check for a cycle.
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if rocks % lcm == 0 and bonus_height == 0:
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key = ''
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for y in range(key_height):
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key += ''.join(chamber.get(Point(x, height - y), ".") for x in range(7))
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key += '\n'
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# Jump forward because we found a cycle, then finish up the simulation.
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if key in tower_hats:
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last_height, last_rocks = tower_hats[key]
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# Deltas from the last time we saw the hat.
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cycle_height = height - last_height
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cycle_rocks = rocks - last_rocks
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# Safe to jump forward this many cycles.
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n_cycles = (target_rocks - rocks) // cycle_rocks
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# Store how much extra height we gained implicitly,
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# otherwise future pieces will spawn way too high
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# compared to the state of the chamber.
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bonus_height += n_cycles * cycle_height
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rocks += n_cycles * cycle_rocks
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else:
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tower_hats[key] = (height, rocks)
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# Spawn new rock.
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curr_rock = [p + N * (height + 4) + (E * 2) for p in ROCKS[rocks % len(ROCKS)]]
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# Try to move the falling rock based on the jet of gas.
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if pattern[move_num % len(pattern)] == '>':
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# Does the right wall block us?
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if any(p.x >= 6 for p in curr_rock):
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pass
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# Does another rock at rest block us?
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elif any(p + E in chamber for p in curr_rock):
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pass
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else:
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curr_rock = [p + E for p in curr_rock]
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else:
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if any(p.x <= 0 for p in curr_rock):
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pass
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elif any(p + W in chamber for p in curr_rock):
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pass
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else:
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curr_rock = [p + W for p in curr_rock]
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# Do we come to rest?
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if any(chamber.get(p + S) == '#' for p in curr_rock):
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for r in curr_rock:
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chamber[r] = "#"
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height = max(height, r.y)
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curr_rock = None
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rocks += 1
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else:
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curr_rock = [r + S for r in curr_rock]
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move_num += 1
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return height + bonus_height
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print("Part 1:", simulate(2022))
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print("Part 2:", simulate(1_000_000_000_000, key_height=16)) # 18 good