aoc2023/AdventOfCode/Day01.cs

using System.Collections;
using System.Text;

namespace AdventOfCode;

public class Day01 : BaseDay
{
    private readonly string _input;
    private int total;
    private int total2;

    public Day01()
    {
        _input = File.ReadAllText(InputFilePath);
        Part1();
        Part2();
    }

    private void Part1()
    {
        StringReader reader = new(_input); //read text file
        string line = reader.ReadLine(); //read first line

        while(line != null) //loop thru file
        {
            StringBuilder build = new();
            string num = ""; //container for ints
            foreach(char c in line)
            {
                if(char.IsDigit(c)) //store each int found in each line
                    num += c;
            }
            line = reader.ReadLine(); //go to next line
            if(num == "") //don't append anything if no ints were found
                continue;
            build.Append(num[0]); //take first digit and put into string
            build.Append(num[^1]); //take second digit and put together with first int
            total += int.Parse(build.ToString()); //add the resulting two digits to the total
        }
    }

    private void Part2()
    {
        StringReader reader = new(_input);
        string line = reader.ReadLine();
        string[] word2num = {"one", "two", "three", "four", "five", "six", "seven", "eight", "nine"};
        //int j = 0;

        while(line != null)
        {
            StringBuilder build = new();
            StringBuilder num = new();
            ArrayList nI = new();
            for (int i = 0; i < line.Length; i++) //look for numbers on line but only ACTUAL digits (not words)
            {
                char c = line.ElementAt(i);
                if(char.IsDigit(c))
                {
                    num.Append(c); //add any digits found to num string
                    //numInd.Append(i); //record index of those digits
                    nI.Add(i);
                }
            }
            int earlyNum = (int)Char.GetNumericValue(num.ToString().ElementAt(0)); //store earliest num found
            int lateNum = (int)Char.GetNumericValue(num.ToString().ElementAt(^1)); //store latest num found
            int earlyNumInd = (int)nI[0]; //store index of earliest num
            int lateNumInd = (int)nI[^1]; //store index of latest num
            foreach (string number in word2num) //look for numbers as words on line (one, two, etc.)
            {
                int currInd = 0;
                while(line.IndexOf(number, currInd) != -1) //while the number can still be found on the line...
                {
                    if(line.IndexOf(number, currInd) < earlyNumInd) //if the number comes before the earliest number
                    {
                        earlyNumInd = line.IndexOf(number, currInd); //replace early number index
                        earlyNum = Array.IndexOf(word2num, number) + 1; //replace early number
                    }
                    if(line.IndexOf(number, currInd) > lateNumInd) //if the number comes after the latest number
                    {
                        lateNumInd = line.IndexOf(number, currInd); //replace the latest number index
                        lateNum = Array.IndexOf(word2num, number) + 1; //replace latest number
                    }
                    currInd = line.IndexOf(number, currInd) + number.Length; //store current index, continue moving through the line
                }
                //check for next number
            }
            line = reader.ReadLine();
            build.Append(earlyNum);
            build.Append(lateNum);
            if(build.ToString() == "")
                continue;
            total2 += int.Parse(build.ToString());
            // Console.WriteLine("Combined numbers: "+build.ToString());
            // Console.WriteLine(total2);
            //j++;
        }
    }

    public override ValueTask<string> Solve_1() => new(total.ToString());

    public override ValueTask<string> Solve_2() => new(total2.ToString());
}