76 lines
2.6 KiB
Python
76 lines
2.6 KiB
Python
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"""
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--- Part Two ---
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As you finish identifying the misplaced items, the Elves come to you
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with another issue.
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For safety, the Elves are divided into groups of three. Every Elf
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carries a badge that identifies their group. For efficiency, within
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each group of three Elves, the badge is the only item type carried by
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all three Elves. That is, if a group's badge is item type B, then all
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three Elves will have item type B somewhere in their rucksack, and at
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most two of the Elves will be carrying any other item type.
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The problem is that someone forgot to put this year's updated
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authenticity sticker on the badges. All of the badges need to be pulled
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out of the rucksacks so the new authenticity stickers can be attached.
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Additionally, nobody wrote down which item type corresponds to each
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group's badges. The only way to tell which item type is the right one
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is by finding the one item type that is common between all three Elves
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in each group.
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Every set of three lines in your list corresponds to a single group,
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but each group can have a different badge item type. So, in the above
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example, the first group's rucksacks are the first three lines:
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vJrwpWtwJgWrhcsFMMfFFhFp
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jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL
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PmmdzqPrVvPwwTWBwg
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And the second group's rucksacks are the next three lines:
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wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn
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ttgJtRGJQctTZtZT
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CrZsJsPPZsGzwwsLwLmpwMDw
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In the first group, the only item type that appears in all three
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rucksacks is lowercase r; this must be their badges. In the second
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group, their badge item type must be Z.
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Priorities for these items must still be found to organize the sticker
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attachment efforts: here, they are 18 (r) for the first group and 52
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(Z) for the second group. The sum of these is 70.
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Find the item type that corresponds to the badges of each three-Elf
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group. What is the sum of the priorities of those item types?
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"""
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import string
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def main():
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total_priority = 0
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priority_index = f"{string.ascii_lowercase}{string.ascii_uppercase}"
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with open("input.txt", "r", encoding="utf-8") as f:
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group = []
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for line in f:
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line_contents = line.strip()
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if not line_contents:
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continue
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group.append(line_contents)
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if len(group) == 3:
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common_item = set(group[0]).intersection(set(group[1])).intersection(set(group[2])).pop()
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common_item_priority = priority_index.index(common_item) + 1
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total_priority += common_item_priority
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group = []
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print(f"Total group priority is {total_priority}")
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if __name__ == "__main__":
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main()
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