35 lines
930 B
Python
35 lines
930 B
Python
#!/usr/bin/env python3
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import re
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from collections import Counter
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lines = (x.strip() for x in open("input.txt"))
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first = next(lines)
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combinations = Counter(first[a:a+2] for a in range(len(first)-1))
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replacements = dict()
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next(lines)
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for line in lines:
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before, insert = re.match(r"([A-Z]{2}) -> ([A-Z])", line).groups()
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replacements[before] = (before[0]+insert, insert+before[1])
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print(combinations)
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for _ in range(40):
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nxt = {}
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for before, afters in replacements.items():
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for after in afters:
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add = combinations.get(before, 0) + nxt.get(after, 0)
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if add:
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nxt[after] = add
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combinations = nxt
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print(combinations)
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letters = {}
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for key, cnt in combinations.items():
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letters[key[0]] = letters.get(key[0], 0) + cnt
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letters[key[1]] = letters.get(key[1], 0) + cnt
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print(letters)
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print((max(*letters.values())+1) // 2 - (min(*letters.values())+1) // 2)
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