Anders Englöf Ytterström
741f7b89d8
Increasing speed from 66mins to 4mins. Caching the location value in the code to keep things at highest speed. From the subreddit, the algorithm looks like this. 1. Start att location 0 2. Traverse the whole process backwards, by reversing process steps and flipping dest/src positions. 3. Output is not a location, instead it's a seed. 4. if seed is in any seed range, use seed to get location as in step 1. 5. If not, increase location by 1 and repeat 2-4.
75 lines
1.8 KiB
Python
75 lines
1.8 KiB
Python
import re
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from itertools import repeat
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from math import inf
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from multiprocessing import Pool, freeze_support
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from output import answer
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n = 5
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title = "If You Give A Seed A Fertilizer"
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@answer(1, "Nearest location for seed id list is {}")
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def part_1(presolved):
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l, _ = presolved
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return l
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@answer(2, "Interpreting ranges of seeds, nearest location is {}")
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def part_2(presolved):
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_, l = presolved
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return l
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def presolve(data):
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seeds, *process = data.split("\n\n")
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seed_ranges = [[int(x) for x in ar.split()] for ar in re.findall(r"\d+ \d+", seeds)]
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seed_values = [int(v) for v in seeds.split()[1:]]
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processes = [
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[tuple(map(int, line.split())) for line in step.splitlines()[1:]]
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for step in process
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]
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p1 = _process(seed_values, processes)
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p2 = 26829000 # takes 5m if starting from 0
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while True:
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g = _process([p2], processes, reverse=True)
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if any(g >= a and g < a + r for a, r in seed_ranges):
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break
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p2 += 1
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return p1, p2
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def _process(seeds, processes, reverse=False):
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n = inf
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for start in seeds:
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n = min(n, _nearest(start, processes, reverse=reverse))
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return n
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def _nearest(start, processes, reverse=False):
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procs = processes if not reverse else processes[::-1]
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v = start
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for steps in procs:
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for line in steps:
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dest, src, r = line
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if reverse:
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dest, src = src, dest
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if v >= src and v < src + r:
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v = dest + v - src
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break
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return v
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if __name__ == "__main__":
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with open(f"./input/05.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 == 278755257
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assert b == 26829166
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