80 lines
2.4 KiB
Python
80 lines
2.4 KiB
Python
import math
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import re
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def main():
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with open("day14.txt", "rt") as input_file:
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lines = [line.rstrip() for line in input_file.readlines()]
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line_re = re.compile(r"(.+) => (.+)")
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raw_transmos = [line_re.match(line).groups() for line in lines]
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transmos = {}
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for inputs, outputs in raw_transmos:
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mult, result = outputs.split(" ")
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input_comps = [i.split(" ") for i in inputs.split(", ")]
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input_tuples = [(int(q), n) for q, n in input_comps]
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transmos[result] = int(mult), input_tuples
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# Part 1
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ore_per_full = get_required_ore(transmos, "FUEL", 1, {})
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print("Required ore for 1 FUEL:", ore_per_full)
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# Part 2
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# Input gives 397771 OPF.
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# 10^12 ores with 13312 OPF example gives 82892753 FUEL.
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# 10^12 ores with 180697 OPF example gives 5586022 FUEL.
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# 10^12 ores with 2210736 OPF example gives 460664 FUEL.
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# 10^12 / 82892753 / 13312 ~= 0.91
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# 10^12 / 5586022 / 180697 ~= 0.99
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# 10^12 / 460664 / 2210736 ~= 0.98
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# Let's say our reaction will have this value at about 0.985.
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# 10^12 / x / 397771 = 0.985 -> x = 2552294
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# Now on to our search.
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fuel = 2552294
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cursor = 10000
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last_result = 0
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min_target = 10**12 - ore_per_full
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max_target = 10**12
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was_below = False
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was_above = False
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while last_result not in range(min_target, max_target):
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last_result = get_required_ore(transmos, "FUEL", fuel, {})
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print("{} FUEL requires {} ORE.".format(fuel, last_result))
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if last_result < min_target:
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if was_above:
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cursor /= 2
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fuel += cursor
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elif last_result > max_target:
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if was_below:
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cursor /= 2
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fuel -= cursor
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def get_required_ore(transmos, name, quantity, leftovers):
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if name == "ORE":
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return quantity
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mult, comps = transmos[name]
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num_reactions = math.ceil(quantity / mult)
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created = 0
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if name in leftovers:
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created += leftovers[name]
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leftovers[name] = 0
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req_ore = 0
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for _ in range(num_reactions):
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if created >= quantity:
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break
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req_ore += sum(get_required_ore(transmos, rn, rq, leftovers) for rq, rn in comps)
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created += mult
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if created > quantity:
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leftover = created - quantity
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leftovers[name] = leftovers.get(name, 0) + leftover
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return req_ore
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if __name__ == "__main__":
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main()
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