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87 lines
2.0 KiB
Python
87 lines
2.0 KiB
Python
#!/usr/bin/env python
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import math
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from collections import defaultdict
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from os.path import dirname, join
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# Day 14
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# Common
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def read_input(filename):
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data = join(dirname(__file__), '..', filename)
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with open(data) as f:
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return f.read().strip()
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test = read_input('test.txt')
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data = read_input('input.txt')
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class Polymer:
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def __init__(self, state: str, insertions: dict[str, str]):
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self.state = state
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self.insertions = insertions
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self.states: defaultdict[str, int] = defaultdict(lambda: 0)
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for i in range(len(self) - 1):
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pair = self.state[i:i+2]
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self.states[pair] += 1
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def __len__(self):
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return len(self.state)
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def step(self):
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new = defaultdict(lambda: 0)
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for state, count in self.states.items():
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if count == 0:
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continue
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insertion = self.insertions[state]
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for key in [state[0] + insertion, insertion + state[1]]:
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new[key] += count
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self.states = new
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def score(self):
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elements = defaultdict(lambda: 0)
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for state, count in self.states.items():
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for element in state:
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elements[element] += count
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for element, count in elements.items():
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elements[element] = math.ceil(elements[element]/2)
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return max(elements.values()) - min(elements.values())
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def flag(self, steps: int):
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for _ in range(steps):
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self.step()
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print(self.score())
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@staticmethod
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def parse(data: str):
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state, raw = data.split('\n\n')
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lines = [
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l.split(' -> ')
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for l in raw.split('\n')
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]
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insertions = {
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i[0]: i[1]
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for i in lines
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}
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return Polymer(state.strip(), insertions)
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# 1
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print('1.')
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polymer = Polymer.parse(test)
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polymer.flag(10)
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polymer = Polymer.parse(data)
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polymer.flag(10)
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# 2
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print('\n2.')
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polymer = Polymer.parse(test)
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polymer.flag(40)
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polymer = Polymer.parse(data)
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polymer.flag(40)
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