You arrive at the airport only to realize that you grabbed your North Pole Credentials instead of your passport. While these documents are extremely similar, North Pole Credentials aren't issued by a country and therefore aren't actually valid documentation for travel in most of the world.

It seems like you're not the only one having problems, though; a very long line has formed for the automatic passport scanners, and the delay could upset your travel itinerary.

Read the full puzzle.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace AdventOfCode.Y2020.Day04;

[ProblemName("Passport Processing")]
class Solution : Solver {

    public object PartOne(string input) => ValidCount(input, cred => 
        rxs.All(kvp => cred.ContainsKey(kvp.Key))
    );
    
    public object PartTwo(string input) => ValidCount(input, cred => 
        rxs.All(kvp =>
            cred.TryGetValue(kvp.Key, out var value) && Regex.IsMatch(value, "^(" + kvp.Value + ")$")
        )
    );

    Dictionary<string, string> rxs = new Dictionary<string, string>(){
        {"byr", "19[2-9][0-9]|200[0-2]"},
        {"iyr", "201[0-9]|2020"},
        {"eyr", "202[0-9]|2030"},
        {"hgt", "1[5-8][0-9]cm|19[0-3]cm|59in|6[0-9]in|7[0-6]in"},
        {"hcl", "#[0-9a-f]{6}"},
        {"ecl", "amb|blu|brn|gry|grn|hzl|oth"},
        {"pid", "[0-9]{9}"},
    };

    int ValidCount(string input, Func<Dictionary<string, string>, bool> isValid) =>
        input
            .Split("\n\n")
            .Select(block => block
                .Split("\n ".ToCharArray())
                .Select(part => part.Split(":"))
                .ToDictionary(parts => parts[0], parts => parts[1]))
            .Count(isValid);
}

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