48 lines
1.3 KiB
Python
48 lines
1.3 KiB
Python
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#!/usr/bin/env python3
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import re
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from collections import defaultdict, deque
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def main(inp):
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with open(inp) as input_rules:
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rules = parse_rules(input_rules)
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reverse_rules = build_reverse_rules(rules)
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print(part1(reverse_rules))
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print(part2(rules, "shiny gold"))
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def parse_rules(input_rules):
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rules = {}
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for input_rule in input_rules:
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color, rule = input_rule.split(" bags contain ")
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rules[color] = {color: int(number) for number, color in re.findall('(\d+) (\w+ \w+)', rule)}
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return rules
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def build_reverse_rules(rules):
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reverse_rules = defaultdict(list)
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for bag, inner_rules in rules.items():
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for c in inner_rules:
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reverse_rules[c].append(bag)
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return reverse_rules
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def part1(reverse_rules):
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queue = deque(("shiny gold",))
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may_contain_shiny_gold = set()
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while queue:
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color = queue.pop()
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for c in reverse_rules.get(color, []):
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if c not in may_contain_shiny_gold:
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may_contain_shiny_gold.add(c)
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queue.appendleft(c)
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return len(may_contain_shiny_gold)
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def part2(rules, color):
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return sum(number + number * part2(rules, c) for c, number in rules[color].items())
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if __name__ == "__main__":
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main("input.txt")
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