44 lines
1.1 KiB
Python
44 lines
1.1 KiB
Python
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import aocd
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import collections
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def parse_rules(orders):
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"""
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Return a dictionary mapping page numbers to lists of page numbers
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For any given key, each page of the value must come after it
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"""
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rules = collections.defaultdict(list)
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for order in orders:
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k,v = order.split('|')
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rules[k].append(v)
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return rules
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def verify_update(update, rules):
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"""
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Ensure that an update is valid using an O(n^2) approach that will
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bite me in the ass in part B somehow
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"""
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update = update.split(',')
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for n, page in enumerate(update):
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for prev_page in update[:n]:
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if prev_page in rules[page]:
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return 0
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return int(update[len(update)//2])
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def solve(data):
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orders, updates = data.split('\n\n')
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rules = parse_rules(orders.split('\n'))
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return sum(verify_update(u, rules) for u in updates.split('\n'))
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if __name__ == '__main__':
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puz = aocd.models.Puzzle(year=2024, day=5)
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# data = puz.examples[0].input_data
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data = puz.input_data
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solution = solve(data)
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print(solution)
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aocd.submit(solution, year=2024, day=5, part='a')
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