Advent of Code 2020 - Day 04

day04_passport_processing.cpp

#include <iostream>
#include <string>
#include <regex>
#include <map>

using namespace std;

const string BYR = "byr:";
const string IYR = "iyr:";
const string EYR = "eyr:";
const string HGT = "hgt:";
const string HCL = "hcl:";
const string ECL = "ecl:";
const string PID = "pid:";

map<string, string> fields = {
    {BYR, "(\\d{4})\\D"},
    {IYR, "(\\d{4})\\D"},
    {EYR, "(\\d{4})\\D"},
    {HGT, "([0-9]+)(in|cm)"},
    {HCL, "#[0-9a-f]{6}\\D"},
    {ECL, "(amb|blu|brn|gry|grn|hzl|oth)"},
    {PID, "\\d{9}\\D"},
};

bool is_present(string &str){
    for(auto &[f, p] : fields){
        if (str.find(f) == string::npos)
            return false;
    }
    return true;
}

bool is_valid(string str){
    for(auto &[f, p] : fields){
        regex pattern(f+p);
        smatch match;
        regex_search(str, match, pattern);
        if(match.empty()) return false;

        int num;
        if (f == BYR){
            num = stoi(match[1]);
            if (num<1920 or num>2002) return false;
        } else if (f == IYR){
            num = stoi(match[1]);
            if(num<2010 or num>2020) return false;
        } else if (f == EYR){
            num = stoi(match[1]);
            if(num<2020 or num>2030) return false;
        } else if (f == HGT){
            num = stoi(match[1]);
            if(match[2]=="cm" and (num<150 or num>193)) return false;
            if(match[2]=="in" and (num<59 or num>76)) return false;
        }
    }
    return true;
}

int main() {
    string passport = "", line;
    int part1_answer = 0, part2_answer = 0;;
    while(getline(cin, line)){
        if (line == ""){
            if (is_present(passport)) part1_answer++;
            if (is_valid(passport)) part2_answer++;
            passport = "";
        } else {
            passport += (line + " ");
        }
    }
    if (is_present(passport)) part1_answer++;
    if (is_valid(passport)) part2_answer++;

    cout << "Part 1: " << part1_answer << "\n";
    cout << "Part 2: " << part2_answer << "\n";
    return 0;
}