61 lines
1.2 KiB
Python
61 lines
1.2 KiB
Python
import re
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from math import lcm
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from output import answer
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n = 8
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title = "Haunted Wasteland"
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@answer(1, "One can reach Z in {} steps")
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def part_1(presolved):
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steps, _ = presolved
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return steps
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@answer(2, "Ghost path takes {} steps before all ghosts are at a Z positon")
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def part_2(presolved):
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_, ghost_meet_point = presolved
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return ghost_meet_point
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def presolve(data):
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d, els = data.split("\n\n")
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r = len(d)
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e = dict()
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for el in els.splitlines():
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k, *lr = re.match(r"(\w+) = \((\w+), (\w+)\)", el).groups()
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e[k] = lr
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p1 = 0
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pos = "AAA"
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while pos != "ZZZ":
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i = 0 if d[p1 % r] == "L" else 1
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pos = e[pos][i]
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p1 += 1
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p2 = 0
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z = list()
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for spos in [p for p in e.keys() if p.endswith("A")]:
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s = 0
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pos = spos
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while not pos.endswith("Z"):
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i = 0 if d[s % r] == "L" else 1
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pos = e[pos][i]
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s += 1
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z.append(s)
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p2 = lcm(*z)
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return p1, p2
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if __name__ == "__main__":
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with open(f"./input/08.txt", "r") as f:
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inp = f.read().strip()
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inp = presolve(inp)
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a = part_1(inp)
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b = part_2(inp)
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assert a == 17141
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assert b == 10818234074807
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