68 lines
1.9 KiB
Python
68 lines
1.9 KiB
Python
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# /usr/bin/env python3
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import re
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from collections import defaultdict
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"""
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identify invalid nearby tickets by considering only whether tickets contain values that are not valid for any field.
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"""
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def main():
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rules, my_ticket, tickets = open("input.txt").read().split("\n\n")
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rules = parse_fields(rules)
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tickets = tickets.splitlines()[1:]
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print("Ticket scanning error rate ", part1(tickets, rules))
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part2(tickets, rules)
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def parse_fields(fields):
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fields_dict = {}
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for field in fields.splitlines():
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k, v = field.split(": ")
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ranges = re.findall(r"(\d+)-(\d+)", v)
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fields_dict[k] = [range(int(r[0]), int(r[1]) + 1) for r in ranges]
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return fields_dict
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def part1(tickets, rules):
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scanning_error_rate = 0
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for ticket in tickets:
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scanning_error_rate += sum(validate_ticket(ticket, rules))
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return scanning_error_rate
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def validate_ticket(ticket, rules):
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invalid_fields = []
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for value in ticket.split(","):
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value = int(value)
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validations = (any(value in r for r in rule) for rule in rules.values())
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if not any(validations):
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invalid_fields.append(value)
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return invalid_fields
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def part2(tickets, rules):
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# filter only valid tickets
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valid_tickets = [ticket for ticket in tickets if validate_ticket(ticket, rules) == []]
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# field => [matching_rules]
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# eliminate field with only one matching rule
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all_matching_rules = {}
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for ticket in valid_tickets:
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possible_matching_rules = defaultdict(set)
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for field_index, field_value in enumerate(ticket.split(",")):
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field_value = int(field_value)
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for name, rule in rules.items():
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match = {r: field_value in r for r in rule}
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if any(match.values()):
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possible_matching_rules[name].add(field_index)
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all_matching_rules[ticket]= possible_matching_rules
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a = 1
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# repeat
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if __name__ == "__main__":
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main()
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