47 lines
1.1 KiB
Python
47 lines
1.1 KiB
Python
from math import prod, sqrt, ceil, floor
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from output import answer
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n = 6
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title = "Wait For It"
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@answer(1, "The product of all record times for all races is {}")
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def part_1(presolved):
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return presolved[0]
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@answer(2, "The product of all record times for the single long race is {}")
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def part_2(presolved):
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return presolved[1]
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def presolve(data):
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values = data.split()
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l = len(values) // 2
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races = list(
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map(
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lambda x: (int(x[0]), int(x[1])), list(zip(values[: l + 1], values[l:]))[1:]
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)
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)
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p1 = prod(sum(bpt * (t - bpt) > d for bpt in range(t)) for t, d in races)
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t = int("".join(values[1:l]))
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d = int("".join(values[l + 1 :]))
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# quadratic formula:
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# https://en.wikipedia.org/wiki/Quadratic_formula
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l = ceil((-t + sqrt(t**2 - 4 * d)) / -2)
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h = floor((-t - sqrt(t**2 - 4 * d)) / -2)
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p2 = h - l + 1
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return p1, p2
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if __name__ == "__main__":
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with open(f"./input/06.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 == 1083852
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assert b == 23501589
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