96 lines
3.1 KiB
Python
96 lines
3.1 KiB
Python
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# SPDX-License-Identifier: MIT
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# Copyright (c) 2020 Akumatic
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#
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#https://adventofcode.com/2020/day/16
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def parseInput(blocks: list) -> dict:
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data = {"rules": dict(), "you": list(), "tickets": list()}
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# 1st block, rules
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for rule in blocks[0]:
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rule = rule.split(": ")
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data["rules"][rule[0]] = []
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vals = [int(n) for r in rule[1].split(" or ") for n in r.split("-")]
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for i in range(0, len(vals), 2):
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data["rules"][rule[0]].append(range(vals[i], vals[i+1] + 1))
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# 2nd block, your ticket
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data["you"] += [int(num) for num in blocks[1][1].split(",")]
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# 3rd block, nearby tickets
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for ticket in blocks[2][1:]:
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data["tickets"].append([int(num) for num in ticket.split(",")])
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return data
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def readFile() -> dict:
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with open(f"{__file__.rstrip('code.py')}input.txt", "r") as f:
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blocks = [block.split("\n") for block in f.read().strip().split("\n\n")]
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return parseInput(blocks)
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def check_rule(rule: list, number: int) -> bool:
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return any([number in r for r in rule])
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def check_rules(rules: dict, number: int) -> bool:
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for rule in rules:
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if check_rule(rules[rule], number):
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return True
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return False
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def validate_ticket(rules: dict, ticket: list) -> bool:
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for number in ticket:
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if not check_rules(rules, number):
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return False
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return True
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def get_valid_tickets(data: dict) -> list:
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valid_tickets = [data["you"]]
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for ticket in data["tickets"]:
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if validate_ticket(data["rules"], ticket):
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valid_tickets.append(ticket)
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return valid_tickets
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def get_possible_positions(rules: dict, valid_tickets: list) -> dict:
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possible_positions = dict()
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size = len(rules)
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for rule in rules:
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pos = []
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for i in range(size):
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if all([check_rule(rules[rule], t[i]) for t in valid_tickets]):
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pos.append(i)
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possible_positions[rule] = pos
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return possible_positions
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def determine_positions(possible_positions: dict) -> dict:
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positions = dict()
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keys = list(possible_positions.keys())
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while keys:
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for key in keys:
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if len(possible_positions[key]) == 1:
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positions[key] = possible_positions[key][0]
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keys.remove(key)
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for pos in keys:
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if positions[key] in possible_positions[pos]:
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possible_positions[pos].remove(positions[key])
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continue
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return positions
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def part1(data: dict) -> int:
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error_rate = 0
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for ticket in data["tickets"]:
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for number in ticket:
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if not check_rules(data["rules"], number):
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error_rate += number
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return error_rate
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def part2(data: dict) -> int:
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valid_tickets = get_valid_tickets(data)
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possible_positions = get_possible_positions(data["rules"], valid_tickets)
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positions = determine_positions(possible_positions)
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result = 1
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for rule in positions:
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if rule.startswith("departure"):
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result *= data["you"][positions[rule]]
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return result
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if __name__ == "__main__":
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input = readFile()
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print(f"Part 1: {part1(input)}")
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print(f"Part 2: {part2(input)}")
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