85 lines
3.2 KiB
Python
85 lines
3.2 KiB
Python
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import re
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from collections import defaultdict
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from solutions import BaseSolution
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class Solution(BaseSolution):
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input_file = "16.txt"
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def __str__(self):
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return "Day 16: Ticket Translation"
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def parse_input(self, data):
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def get_ranges(line):
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label = line.split(":")[0]
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r1a, r1b, r2a, r2b = re.findall(rxranges, line.strip())
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return (label, range(int(r1a), int(r1b) + 1), range(int(r2a), int(r2b) + 1))
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rxranges = r"([0-9]+)"
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ranges, golden_ticket, other_tickets = data.split("\n\n")
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ranges = [*map(get_ranges, ranges.splitlines())]
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golden_ticket = [*map(int, golden_ticket.splitlines()[1].split(","))]
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other_tickets = [
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[*map(int, ticket.split(","))] for ticket in other_tickets.splitlines()[1:]
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]
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return (ranges, golden_ticket, other_tickets)
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def get_invalid_values(self, ranges, ticket):
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def not_in_any_range(x):
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return all(x not in r1 and x not in r2 for _, r1, r2 in ranges)
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return [*filter(not_in_any_range, ticket)]
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def solve(self, puzzle_input):
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ranges, _, tickets = puzzle_input
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error_rate = 0
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valid_tickets = []
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for ticket in tickets:
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error_rate += sum(self.get_invalid_values(ranges, ticket))
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return error_rate
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def solve_again(self, puzzle_input):
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ranges, golden_ticket, tickets = puzzle_input
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valid_tickets = []
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for ticket in tickets:
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if len(self.get_invalid_values(ranges, ticket)) == 0:
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valid_tickets.append(ticket)
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sorted_ranges = self.get_positions(ranges, valid_tickets)
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factors = [i for i, r in enumerate(sorted_ranges) if "departure" in r]
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m = 1
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for f in factors:
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m *= golden_ticket[f]
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return m
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def get_positions(self, ranges, valid_tickets):
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columns = [*zip(*valid_tickets)]
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matches = defaultdict(lambda: set())
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# Step 1: find all possible range matches for columns
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# Example: {'row': {0, 1, 2}, 'class': {1, 2}, 'seat': {2}}
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for e, column in enumerate(columns):
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for column_name, r1, r2 in ranges:
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if all(x in r1 or x in r2 for x in column):
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matches[column_name].add(e)
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# Step 2: collect all columns with only one matching range, and subtract
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# these ranges from the columns having multiple ranges. Repeat until all
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# columns only have one matching range.
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# Example:
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# #1: {'row': {0, 1, 2}, 'class': {1, 2}, 'seat': {2}}
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# #2: {'row': {0, 1}, 'class': {1}, 'seat': {2}}
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# #3: {'row': {0}, 'class': {1}, 'seat': {2}}
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while any(len(v) > 1 for _k, v in matches.items()):
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singles = set({}).union(*[v for _k, v in matches.items() if len(v) == 1])
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for m in matches:
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if len(matches[m]) > 1:
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matches[m] = matches[m] - singles
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# step 3: Sort the matches list and return a list only containing the
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# column names.
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final = sorted([(k, v.pop()) for k, v in matches.items()], key=lambda kv: kv[1])
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return [k for k, _v in final]
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if __name__ == "__main__":
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solution = Solution()
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solution.show_results()
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