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Discussion on: Advent of Code 2020 Solution Megathread - Day 4: Passport Processing

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aspittel profile image
Ali Spittel

I hate problems like this:

class Validator:
    def __init__(self, passport):
        self.passport = passport

    def check_field_count(self):
        return len(self.passport) == 8 or (len(self.passport) == 7 and 'cid' not in self.passport)

    def check_year(self, key, start, end):
        return len(self.passport[key]) == 4 and int(self.passport[key]) >= start and int(self.passport[key]) <= end

    def check_byr(self):
        return self.check_year('byr', 1920, 2002)

    def check_iyr(self):
        return self.check_year('iyr', 2010, 2020)

    def check_eyr(self):
        return self.check_year('eyr', 2020, 2030)

    def check_hcl(self):
        return self.passport['hcl'][0] == "#" and self.passport['hcl'][1:].isalnum()

    def check_ecl(self):
        return self.passport['ecl'] in ['amb', 'blu', 'brn', 'gry', 'grn', 'hzl', 'oth']

    def check_pid(self):
        return len(self.passport['pid']) == 9

    def check_hgt(self):
        if self.passport['hgt'][-2:] == "cm":
            return int(self.passport['hgt'][:-2]) >= 150 and int(self.passport['hgt'][:-2]) <= 193
        elif self.passport['hgt'][-2:] == "in":
            return int(self.passport['hgt'][:-2]) >= 59 and int(self.passport['hgt'][:-2]) <= 76

    def is_valid(self):
        return (self.check_field_count() and self.check_byr() and self.check_iyr() and self.check_eyr() 
            and self.check_hcl() and self.check_ecl() and self.check_pid() and self.check_hgt())


def get_passports(inp):
    passports = []
    passport = {}
    for line in inp:
        if line != "\n":
            line = line.rstrip().split(" ")
            line = [field.split(":") for field in line]
            for field in line:
                passport[field[0]] = field[1]
        else:
            passports.append(passport)
            passport = {}
    passports.append(passport)
    return passports


with open('input.txt') as inp:
    passports = get_passports(inp)
    validators = [Validator(passport) for passport in passports]
    part_1_count = 0
    part_2_count = 0
    for validator in validators:
        if validator.check_field_count(): 
            part_1_count += 1
        if validator.is_valid(): 
            part_2_count += 1                        

    print(part_1_count) 
    print(part_2_count)                
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grantfinneman profile image
Grant Finneman

Thank you so much for the clear and concise python, I'm new to python and thought this would be an excellent way to learn it. I figured this one out eventually and thought I would come here to see how someone else did it. I don't understand how yours doesn't throw a key error when trying to access dictionary keys that aren't there. I need to learn more about classes but I don't know why this works. If you could point me in the right direction I'd greatly appreciate it. Thank you again for the wonderful example