AdventOfCode23/Day8/MapData.cs

namespace Day8;

public class MapData
{
    public string Instructions { get; }
    public Node Start { get; }

    public MapData(string instructions, Node start)
    {
        Instructions = instructions;
        Start = start;
    }

    public long Walk()
    {
        var current = Start;
        var steps = 0L;

        while (current.Name != "ZZZ")
        {
            if (steps >= 1000000)
            {
                throw new Exception("Over ONE MILLION");
            }
            
            var instruction = Instructions[(int)(steps % Instructions.Length)];
            if (instruction != 'L' && instruction != 'R')
            {
                throw new Exception($"Unknown instruction: {instruction} @ {steps}");
            }
            
            Console.WriteLine($"{current.Name} => {instruction}");
            
            steps++;
            current = instruction == 'L' ? current.Left : current.Right;
            
            if (current == null)
            {
                throw new Exception($"Ended in null after: {instruction} @ {steps}");
            }
        }

        return steps;
    }
}