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64 lines
1.4 KiB
Python
64 lines
1.4 KiB
Python
3 years ago
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import re
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from collections import defaultdict
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INPUT_FILENAME = "example"
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def parse_atoms(molecule):
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"""Return a list of all Atoms in the molecule string"""
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return re.findall(r"[A-Z][a-z]*", molecule)
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ATOMS = set()
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REPLACEMENTS = list()
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with open(INPUT_FILENAME) 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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REPLACEMENTS.append([atom, decays_to])
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ATOMS.update(parse_atoms(decays_to))
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ATOMS.add(atom)
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line = f.readline()
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MOLECULE = f.readline().strip()
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ATOMS.update(parse_atoms(MOLECULE))
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print("ATOMS", ATOMS)
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print()
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print("REPLACEMENTS", REPLACEMENTS)
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print()
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print("MOLECULE", MOLECULE)
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print()
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def shrink(molecule, from_molecule, to_atom, idx):
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prefix = molecule[:idx]
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suffix = molecule[idx + len(from_molecule) :]
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return prefix + to_atom + suffix
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def step(molecule):
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next_molecules = []
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for (atom, decays_to) in REPLACEMENTS:
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possible = [m.start() for m in re.finditer(decays_to, molecule)]
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if not possible:
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continue
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print(decays_to, atom)
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if atom == "e" and len(decays_to) != len(molecule):
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continue
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for idx in possible:
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next_molecule = shrink(molecule, decays_to, atom, idx)
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next_molecules.append(next_molecules)
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print(" ", idx, next_molecule)
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return next_molecules
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step(MOLECULE)
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