Part 1 Day 9

AdventOfCode/Problems/AOC2024/Day7/BridgeRepair.cs

@@ -21,7 +21,6 @@ internal class BridgeRepair : Problem<ulong, ulong>
 		}
 	}
 
-	//This does not work
 	public override void CalculatePart2()
 	{
 		foreach (var (target, nums) in _data)

AdventOfCode/Problems/AOC2024/Day9/DiskFragmenter.cs

@@ -1,25 +1,248 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 
 namespace AdventOfCode.Problems.AOC2024.Day9;
-//[ProblemInfo(2024, 9, "Disk Fragmenter")]
+
-internal class DiskFragmenter : Problem
+[ProblemInfo(2024, 9, "Disk Fragmenter")]
+internal class DiskFragmenter : Problem<long, long>
 {
+	private int[] _data = [];
+
 	public override void CalculatePart1()
 	{
-		throw new NotImplementedException();
+		var data = Expand(_data);
+		Compact(data);
+		Part1 = ComputeHash(data);
 	}
 
 	public override void CalculatePart2()
 	{
-		throw new NotImplementedException();
+		var blocks = ExpandBlocks(_data);
+		CompactV2(blocks);
+		//Print(blocks);
+		// Too High: 8838426222802
+		Part2 = ComputeHashV2(blocks);
+	}
+
+	public static void Print(List<Block> blocks, int idx = -1)
+	{
+		for (int i = 0; i < blocks.Count; i++)
+		{
+			Console.ResetColor();
+			if(i == idx)
+				Console.BackgroundColor = ConsoleColor.Green;
+			if (blocks[i].isEmpty)
+				Console.ForegroundColor = ConsoleColor.DarkGray;
+			Console.Write(blocks[i].ToString());
+		}
+		Console.ResetColor();
+		Console.WriteLine();
+	}
+
+	public static void Print(int[] data)
+	{
+		Console.WriteLine(data.Select(x => x == -1 ? " " : x.ToString()).AsJoinedString("").Trim());
+	}
+
+	public static int[] Expand(int[] data)
+	{
+		var result = new List<int>(data.Sum());
+		var isFile = true;
+		var id = 0;
+		foreach (var item in data)
+		{
+			if (isFile)
+				result.AddRange(Enumerable.Repeat(id++, item));
+			else
+				result.AddRange(Enumerable.Repeat(-1, item));
+			isFile = !isFile;
+		}
+		return [.. result];
+	}
+
+	public static void Compact(int[] data)
+	{
+		var readPos = data.Length - 1;
+		var writePos = 0;
+		var curValue = 0;
+		var isWriting = false;
+		while (true)
+		{
+			if (readPos - 2 < writePos && !isWriting)
+				break;
+			if (isWriting)
+			{
+				while (writePos < data.Length)
+				{
+					if (data[writePos] == -1)
+					{
+						data[writePos] = curValue;
+						data[readPos] = -1;
+						curValue = -1;
+						writePos++;
+						break;
+					}
+					writePos++;
+				}
+				isWriting = false;
+			}
+			else
+			{
+				do
+				{
+					curValue = data[readPos];
+					if (curValue != -1)
+					{
+						isWriting = true;
+						break;
+					}
+					readPos--;
+				}
+				while (readPos >= 0);
+			}
+		}
+	}
+
+	public static long ComputeHash(int[] data)
+	{
+		long hash = 0;
+		//Compensate to incomplete compaction
+		long idx = 0;
+		for (long i = 0; i < data.Length; i++)
+		{
+			if (data[i] == -1)
+				continue;
+			hash += (idx++) * (long)data[i];
+		}
+		return hash;
+	}
+
+	public static List<Block> ExpandBlocks(int[] data)
+	{
+		var blocks = new List<Block>();
+		var isFile = true;
+		var id = 0;
+		foreach (var block in data)
+		{
+			if (block == 0)
+			{
+				isFile = !isFile;
+				continue;
+			}
+			if (isFile)
+				blocks.Add(new Block(id++, block));
+			else
+				blocks.Add(new Block(block));
+			isFile = !isFile;
+		}
+		return blocks;
+	}
+
+	public static void CompactV2(List<Block> blocks)
+	{
+		for (int idx = blocks.Count - 1; idx >= 0; idx--)
+		{
+			var block = blocks[idx];
+			if (block.isEmpty)
+				continue;
+			var emptyPos = FindFirstEmptyBlock(block.length, idx, blocks);
+			if (emptyPos == -1)
+				continue;
+			var emptyBlock = blocks[emptyPos];
+			//Replace Empty Block
+			if (emptyBlock.length == block.length)
+				blocks[emptyPos] = block;
+			else
+			{
+				//Insert and Shrink Empty Block
+				blocks.Insert(emptyPos, block);
+				idx += 1;
+				emptyBlock.length -= block.length;
+			}
+
+			//Merge Left and Right empty blocks
+			if (idx + 1 < blocks.Count && blocks[idx + 1].isEmpty && idx - 1 > 0 && blocks[idx - 1].isEmpty)
+			{
+				blocks[idx - 1].length += block.length + blocks[idx + 1].length;
+				blocks.RemoveAt(idx);
+				blocks.RemoveAt(idx);
+				idx -= 1;
+			}
+			//Extend Right Block
+			else if (idx + 1 < blocks.Count && blocks[idx + 1].isEmpty)
+				blocks[idx + 1].length += block.length;
+			//Extend Left Block
+			else if (idx - 1 > 0 && blocks[idx - 1].isEmpty)
+				blocks[idx - 1].length += block.length;
+			//Insert new Empty Block
+			else
+				blocks[idx] = new Block(block.length);
+			//Print(blocks, idx);
+		}
+
+		static int FindFirstEmptyBlock(int length, int limit, List<Block> blocks)
+		{
+			for (int i = 0; i < limit; i++)
+			{
+				var block = blocks[i];
+				if (block.isEmpty && block.length >= length)
+					return i;
+			}
+			return -1;
+		}
+	}
+
+	public static long ComputeHashV2(List<Block> blocks)
+	{
+		long hash = 0;
+		long pos = 0;
+		for (int i = 0; i < blocks.Count; i++)
+		{
+			var block = blocks[i];
+			if (!block.isEmpty)
+			{
+				//There's probably an equation for this
+				for (int x = 0; x < block.length; x++)
+				{
+					hash += block.id * pos++;
+				}
+			}else
+				pos += block.length;
+		}
+
+		return hash;
 	}
 
 	public override void LoadInput()
 	{
-		throw new NotImplementedException();
+		_data = ReadInputText("input.txt").Select(x => (int)(x - '0')).ToArray();
 	}
 }
+
+public class Block
+{
+	public bool isEmpty;
+	public int id;
+	public int length;
+
+	public Block(int id, int length)
+	{
+		this.id = id;
+		this.length = length;
+	}
+
+	public Block(int length)
+	{
+		isEmpty = true;
+		this.length = length;
+	}
+
+	public override string ToString()
+	{
+		return isEmpty ? $"[{length}]" : $"{id}:{length}";
+	}
+}

AdventOfCode/Program.cs

@@ -1,5 +1,7 @@
 global using AdventOfCode.Runner;
 global using AdventOfCode.Runner.Attributes;
+global using AdventOfCode.Utils;
+
 
 var runner = new AOCRunner();
 runner.RenderInteractiveMenu();

AdventOfCode/Utils/Extensions.cs

@@ -7,7 +7,9 @@ using System.Threading.Tasks;
 namespace AdventOfCode.Utils;
 public static class Extensions
 {
-	public static string AsJoinedString(this object[] data, string delim = ", ")
+
+
+	public static string AsJoinedString<T>(this IEnumerable<T> data, string delim = ", ")
 	{
 		return string.Join(delim, data);
 	}