AdventOfCode2023Part1Part2

using System;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

namespace AdventOfCodeDay1
{
    class Solution
    {
        public object PartOne(string input) =>
            Solve(input, @"\d");

        public object PartTwo(string input) =>
            Solve(input, @"\d|one|two|three|four|five|six|seven|eight|nine");

        int Solve(string input, string rx) => (
            from line in input.Split("\n")
            let first = Regex.Match(line, rx)
            let last = Regex.Match(line, rx, RegexOptions.RightToLeft)
            select ParseMatch(first.Value) * 10 + ParseMatch(last.Value)
        ).Sum();

        int ParseMatch(string st) => st switch
        {
            "one" => 1,
            "two" => 2,
            "three" => 3,
            "four" => 4,
            "five" => 5,
            "six" => 6,
            "seven" => 7,
            "eight" => 8,
            "nine" => 9,
            var d => int.Parse(d)
        };
    }

    class Program
    {
        static void Main(string[] args)
        {
            string filePath = "input.txt";

            if (!File.Exists(filePath))
            {
                Console.WriteLine("Файлът input.txt не е намерен!");
                return;
            }

            string input = File.ReadAllText(filePath);
            var solution = new Solution();

            Console.WriteLine($"Part One: {solution.PartOne(input)}");
            Console.WriteLine($"Part Two: {solution.PartTwo(input)}");
        }
    }
}