64 lines
1.3 KiB
Python
64 lines
1.3 KiB
Python
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#!/usr/bin/env python
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import re
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from collections import defaultdict
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RE_INS = re.compile("(.*)\s+->\s+(.*)$")
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def tokenize_polymer(polymer):
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result = defaultdict(int)
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for i in range(0, len(polymer)-1):
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k = polymer[i:i+2]
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result[k] += 1
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return result
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def iterate_polymer(polymer, rules):
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delta = defaultdict(int)
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pairs = list(polymer.keys())
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for pair in pairs:
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if pair not in rules:
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continue
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if polymer[pair] == 0:
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continue
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p1 = pair[0]+rules[pair]
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p2 = rules[pair]+pair[1]
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delta[p1] += polymer[pair]
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delta[p2] += polymer[pair]
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delta[pair] -= polymer[pair]
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for pair in delta:
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polymer[pair] += delta[pair]
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return polymer
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polymer = None
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rules = dict()
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polymer_pairs = defaultdict(int)
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with open("input01.txt","r") as f:
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polymer = f. readline().strip()
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for line in f:
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line = line.strip()
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if len(line) == 0:
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continue
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m = RE_INS.match(line)
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if not m:
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print(line)
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rules[m.group(1)] = m.group(2)
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for i in range(0, len(polymer)-1):
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k = polymer[i:i+2]
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polymer_pairs[k] += 1
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polymer_pairs = tokenize_polymer(polymer)
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for i in range(40):
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polymer_pairs = iterate_polymer(polymer_pairs, rules)
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# print(polymer_pairs)
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sums = defaultdict(int)
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for i in polymer_pairs.keys():
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sums[i[1]] += polymer_pairs[i]
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sums[polymer[0]] += 1
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p_max = max([x for x in sums.values()])
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p_min = min([x for x in sums.values()])
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print(p_max - p_min)
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