Day4.java

package com.sbaars.adventofcode.year20.days;

import com.sbaars.adventofcode.year20.Day2020;

import java.util.Arrays;
import java.util.Map;
import java.util.function.Predicate;
import java.util.regex.Pattern;

import static java.util.stream.Collectors.toSet;

public class Day4 extends Day2020 {
  private static final Map<String, String> expected = Map.of("byr", "^(200[0-2]|19[2-9][0-9])$",
      "iyr", "^(2020|201[0-9])$",
      "eyr", "^(2030|202[0-9])$",
      "hgt", "^((1([5-8][0-9]|9[0-3])cm)|((59|6[0-9]|7[0-6])in))$",
      "hcl", "^(#[0-9a-f]{6})$",
      "ecl", "^(amb|blu|brn|gry|grn|hzl|oth)$",
      "pid", "^[0-9]{9}$");

  public Day4() {
    super(4);
  }

  public static void main(String[] args) {
    new Day4().printParts();
  }

  @Override
  public Object part1() {
    return verifyPassports(this::valid1);
  }

  @Override
  public Object part2() {
    return verifyPassports(this::valid2);
  }

  public long verifyPassports(Predicate<String[]> verifyFunction) {
    String[][] passports = Arrays.stream(day().split("\n\n")).map(str -> str.replace("\n", " ")).map(str -> str.split(" ")).toArray(String[][]::new);
    return Arrays.stream(passports).filter(verifyFunction).count();
  }

  public boolean valid1(String[] passport) {
    return Arrays.stream(passport).map(s -> s.substring(0, 3)).collect(toSet()).containsAll(expected.keySet());
  }

  public boolean valid2(String[] passport) {
    return valid1(passport) && Arrays.stream(passport).map(s -> s.split(":")).allMatch(s -> matchesRegex(s[0], s[1]));
  }

  public boolean matchesRegex(String key, String validate) {
    if (!expected.containsKey(key)) return true;
    final Pattern pattern = Pattern.compile(expected.get(key));
    return pattern.matcher(validate).matches();
  }
}