Advent-of-Code/2020/Day 4/Solution.py

import re

input_file = "input.txt"

height_re = re.compile(r'^([0-9]+)(in|cm)$')
passport_id_re = re.compile(r'^[0-9]{9}$')
color_re = re.compile(r'^#[0-9a-f]{6}$')


def check_limits(to_test, min_valid, max_valid):
    return False if (to_test < min_valid or to_test > max_valid) else True


def validate_passport(record):
    for field in record:
        if field[0] == "byr":
            if not check_limits(int(field[1]), 1920, 2002):
                return False
        elif field[0] == "iyr":
            if not check_limits(int(field[1]), 2010, 2020):
                return False
        elif field[0] == "eyr":
            if not check_limits(int(field[1]), 2020, 2030):
                return False
        elif field[0] == "hgt":
            regex_match = height_re.match(field[1])
            if not regex_match:
                return False
            if regex_match.groups()[1] == "cm" and not check_limits(int(regex_match.groups()[0]), 150, 193):
                return False
            elif regex_match.groups()[1] == "in" and not check_limits(int(regex_match.groups()[0]), 59, 76):
                return False
        elif field[0] == "hcl":
            regex_match = color_re.match(field[1])
            if not regex_match:
                return False
        elif field[0] == "ecl":
            if field[1] not in ["amb", "blu", "brn", "gry", "grn", "hzl", "oth"]:
                return False
        elif field[0] == "pid":
            regex_match = passport_id_re.match(field[1])
            if not regex_match:
                return False

    return True


records = [[]]

valid_passports = 0

with open(input_file) as passports:
    line = passports.readline()
    current_index = 0
    while line:
        if line == "\n":
            records.append([])
            current_index += 1
            line = passports.readline()
            continue

        # rstrip() strips the string from end of line characters et alia.
        for raw_entry in line.rstrip().split(" "):
            # Split the different fields, then split them in (key,value) tuples
            records[current_index].append(tuple(raw_entry.split(":")))

        line = passports.readline()

for record in records:
    if len(record) == 8:
        if validate_passport(record):
            valid_passports += 1
    if len(record) == 7:
        is_north_pole_credential = True
        for field in record:
            if field[0] == "cid":
                is_north_pole_credential = False
                break
        if is_north_pole_credential and validate_passport(record):
            valid_passports += 1

print(f"There are {valid_passports} valid passports out of {len(records)}")