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36 lines
735 B
Python
36 lines
735 B
Python
3 years ago
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import re
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from collections import defaultdict
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def parse_atoms(molecule):
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return re.findall(r"[A-Z][a-z]*", molecule)
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decay = defaultdict(list)
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with open("input") as f:
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line = f.readline()
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while line != "\n":
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atom, decays_to = line.strip().split(" => ")
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decay[atom].append(decays_to)
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line = f.readline()
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molecule = f.readline()
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print(decay)
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print()
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print(molecule)
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atoms = parse_atoms(molecule)
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next_molecules = set()
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for idx, atom in enumerate(atoms):
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prefix = "".join(atoms[:idx])
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suffix = "".join(atoms[idx + 1 :])
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for decay_molecule in decay[atom]:
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descendant = prefix + decay_molecule + suffix
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next_molecules.add(descendant)
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print(len(next_molecules))
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