day4.py

# https://adventofcode.com/2020/day/4

from operator import methodcaller
from pathlib import Path

INPUT_FILE = Path(__file__).parent / "input.txt"

class Document:
    PASSPORT_KEYS = {
        "byr", # (Birth Year)
        "iyr", # (Issue Year)
        "eyr", # (Expiration Year)
        "hgt", # (Height)
        "hcl", # (Hair Color)
        "ecl", # (Eye Color)
        "pid", # (Passport ID)
        "cid", # (Country ID)
    }

    NORTHPOLE_CREDENTIALS = PASSPORT_KEYS - {"cid"}

    def __init__(self, mapping):
        self.mapping = mapping

    def is_valid(self):
        validators = [
            getattr(self, name) for name in dir(self)
            if name.startswith("has_valid")
        ]
        return (
            self.has_valid_keys()
            and all(valid() for valid in validators)
        )

    def has_valid_keys(self):
        return (
            self.mapping.keys() == self.PASSPORT_KEYS
            or self.mapping.keys() == self.NORTHPOLE_CREDENTIALS
        )

    def has_valid_birth_year(self):
        return 1920 <= int(self.mapping["byr"]) <= 2002

    def has_valid_issue_year(self):
        return 2010 <= int(self.mapping["iyr"]) <= 2020

    def has_valid_expiration_year(self):
        return 2020 <= int(self.mapping["eyr"]) <= 2030

    def has_valid_height(self):
        height = self.mapping["hgt"][:-2]
        unit = self.mapping["hgt"][-2:]
        return (
            unit == "cm" and 150 <= int(height) <= 193
            or unit == "in" and 59 <= int(height) <= 76
        )

    def has_valid_hair_color(self):
        prefix, *code = self.mapping["hcl"]
        allowed = set("0123456789abcdef")
        return (
            prefix == "#" and len(code) == 6
            and set(code) <= allowed
        )

    def has_valid_eye_color(self):
        valid_colors = [
            "amb", "blu", "brn", "gry", "grn", "hzl", "oth"
        ]
        return self.mapping["ecl"] in valid_colors

    def has_valid_passport_id(self):
        pid = self.mapping["pid"]
        return pid.isdigit() and len(pid) == 9

    @classmethod
    def from_stream(cls, stream):
        mapping = {}
        for line in stream:
            if not line.strip():
                break
            for part in line.split():
                key, value = part.split(":")
                mapping[key] = value
        return cls(mapping)

def get_documents(stream):
    while True:
        document = Document.from_stream(stream)
        if not document.mapping:
            break
        yield document

def main():
    with INPUT_FILE.open() as stream:
        documents = list(get_documents(stream))
    for validator in ("has_valid_keys", "is_valid"):
        num_valid = sum(map(methodcaller(validator), documents))
        print(validator, num_valid)