AdventOfCode/Days/Day10.cs

using Spectre.Console;

namespace AdventOfCode.Days;

public class Day10 : Day
{
    public override int Number => 10;
    public override string Name => "Cathode-Ray Tube";
    public override void RunPart1(bool display = true)
    {
        int cycle = 1;
        int x = 1;
        long sum = 0;

        // Increment sum when needed
        void IncrementCycle()
        {
            cycle++;

            // Check for signal stength at the start of a cycle
            if ((cycle + 20) % 40 == 0)
            {
                sum += x * cycle;
            }
        }

        foreach (var line in Input.ReadAllLines())
        {
            // noop
            if (line == "noop")
            {
                // noop finished, go to next cycle
                IncrementCycle();
            }
            // addx
            else
            {
                var split = line.Split(' ');
                var v = int.Parse(split[1]);

                // Prepare addx
                IncrementCycle();

                // addx finished, add to x and then go to next cycle
                x += v;
                IncrementCycle();
            }
        }

        if (display)
        {
            AnsiConsole.MarkupLine($"[green]Sum of signal strengths: [yellow]{sum}[/][/]");
        }
    }

    public override void RunPart2(bool display = true)
    {
        // Setup the CRT
        const char litPixel = '#';
        const char darkPixel = '.';

        const int rowCount = 6;
        const int columnCount = 40;
        var crt = new char[rowCount, columnCount];
        var crtCanvas = new Canvas(columnCount, rowCount);

        // Now cycle is the position where the CRT is drawing (need to offset by 1 in the grid)
        int cycle = 1;
        // x is the position of the sprite
        int x = 1;

        // Draw first pixel
        crt[0, 0] = litPixel;
        crtCanvas.SetPixel(0, 0, Color.Red);

        // Increment sum when needed
        void IncrementCycle()
        {
            cycle++;

            // We're done drawing the crt
            if (cycle > 240)
            {
                return;
            }

            // Draw a white or black pixel
            int row = (cycle - 1) / columnCount;
            int column = (cycle - 1) % columnCount;

            // The CRT is drawing on the sprite
            if (column == x - 1 || column == x || column == x + 1)
            {
                crt[row, column] = litPixel;
                crtCanvas.SetPixel(column, row, (cycle + row) % 2 == 0 ? Color.Green : Color.Red);
            }
            else
            {
                crt[row, column] = darkPixel;
                crtCanvas.SetPixel(column, row, Color.Black);
            }
        }

        foreach (var line in Input.ReadAllLines())
        {
            // noop
            if (line == "noop")
            {
                // noop finished, go to next cycle
                IncrementCycle();
            }
            // addx
            else
            {
                var split = line.Split(' ');
                var v = int.Parse(split[1]);

                // Prepare addx
                IncrementCycle();

                // addx finished, add to x and then go to next cycle
                x += v;
                IncrementCycle();
            }
        }

        // Print the CRT
        if (display)
        {
            AnsiConsole.Write(crtCanvas);
        }
    }

    #region Input

    public const string Input =
    """
    noop
    noop
    addx 15
    addx -10
    noop
    noop
    addx 3
    noop
    noop
    addx 7
    addx 1
    addx 4
    addx -1
    addx 1
    addx 5
    addx 1
    noop
    noop
    addx 5
    addx -1
    noop
    addx 3
    noop
    addx 3
    addx -38
    noop
    addx 3
    addx 2
    addx 5
    addx 2
    addx 26
    addx -21
    addx -2
    addx 5
    addx 2
    addx -14
    addx 15
    noop
    addx 7
    noop
    addx 2
    addx -22
    addx 23
    addx 2
    addx 5
    addx -40
    noop
    noop
    addx 3
    addx 2
    noop
    addx 24
    addx -19
    noop
    noop
    noop
    addx 5
    addx 5
    addx 2
    noop
    noop
    noop
    noop
    addx 7
    noop
    addx 3
    noop
    addx 3
    addx -2
    addx 2
    addx 5
    addx -38
    noop
    noop
    noop
    addx 5
    addx 2
    addx -1
    addx 2
    addx 30
    addx -23
    noop
    noop
    noop
    noop
    addx 3
    addx 5
    addx -11
    addx 12
    noop
    addx 6
    addx 1
    noop
    addx 4
    addx 3
    noop
    addx -40
    addx 4
    addx 28
    addx -27
    addx 5
    addx 2
    addx 5
    noop
    noop
    addx -2
    addx 2
    addx 5
    addx 3
    noop
    addx 2
    addx -25
    addx 30
    noop
    addx 3
    addx -2
    addx 2
    addx 5
    addx -39
    addx 29
    addx -27
    addx 5
    noop
    noop
    noop
    addx 4
    noop
    addx 1
    addx 2
    addx 5
    addx 2
    noop
    noop
    noop
    noop
    addx 5
    addx 1
    noop
    addx 2
    addx 5
    addx -32
    addx 34
    noop
    noop
    noop
    noop
    """;

    #endregion
}