From de2ce7e9b02d7d714fccd7980e9e2652c0136e5b Mon Sep 17 00:00:00 2001
From: Rob Stoffelen <r.stoffelen@my-lex.nl>
Date: Thu, 15 Dec 2022 09:34:57 +0100
Subject: [PATCH] Completed Day 9 p 2

---
 Advend Of Code Runner/Program.cs              |  2 +-
 .../2022/Day 09/Day09Part1.cs                 |  2 +-
 .../2022/Day 09/Day09Part2.cs                 | 11 ++----
 .../2022/Day 09/RopeWalker.cs                 | 39 ++++++++++++-------
 4 files changed, 30 insertions(+), 24 deletions(-)

diff --git a/Advend Of Code Runner/Program.cs b/Advend Of Code Runner/Program.cs
index 1fae6ed..d6738d9 100644
--- a/Advend Of Code Runner/Program.cs	
+++ b/Advend Of Code Runner/Program.cs	
@@ -12,7 +12,7 @@ D 1
 L 5
 R 2";
 
-Answerable answerable = new Day09Part1();
+Answerable answerable = new Day09Part2();
 byte[] dataArray = File.ReadAllBytes(answerable.DefaultInputFile);
 //dataArray = Encoding.UTF8.GetBytes(_demoData);
 
diff --git a/Advent Of Code Library/2022/Day 09/Day09Part1.cs b/Advent Of Code Library/2022/Day 09/Day09Part1.cs
index eae0de9..25c9465 100644
--- a/Advent Of Code Library/2022/Day 09/Day09Part1.cs	
+++ b/Advent Of Code Library/2022/Day 09/Day09Part1.cs	
@@ -14,7 +14,7 @@
             string[] movements = GetAsStringArray(data);
             RopeWalker walker = new();
 
-            return walker.ProcessMovement(movements).ToString();
+            return walker.ProcessMovement(movements, 2).ToString();
         }
     }
 }
diff --git a/Advent Of Code Library/2022/Day 09/Day09Part2.cs b/Advent Of Code Library/2022/Day 09/Day09Part2.cs
index f3f07db..d538483 100644
--- a/Advent Of Code Library/2022/Day 09/Day09Part2.cs	
+++ b/Advent Of Code Library/2022/Day 09/Day09Part2.cs	
@@ -1,5 +1,6 @@
 namespace AdventOfCodeLibrary._2022
 {
+    using AdventOfCodeLibrary._2022.Day_09;
     using AdventOfCodeLibrary.Shared;
 
     public class Day09Part2 : Answerable
@@ -10,14 +11,10 @@
 
         public override string GetAnswer(byte[] data)
         {
-            int markerLength = 14;
-            for (int skip = 0; skip < data.Length - 1 - markerLength; skip++)
-            {
-                if (data.Skip(skip).Take(markerLength).Distinct().Count() == markerLength)
-                    return (skip + markerLength).ToString();
-            }
+            string[] movements = GetAsStringArray(data);
+            RopeWalker walker = new();
 
-            return "nothing found";
+            return walker.ProcessMovement(movements, 10).ToString();
         }
     }
 }
diff --git a/Advent Of Code Library/2022/Day 09/RopeWalker.cs b/Advent Of Code Library/2022/Day 09/RopeWalker.cs
index 0e65621..98f2c13 100644
--- a/Advent Of Code Library/2022/Day 09/RopeWalker.cs	
+++ b/Advent Of Code Library/2022/Day 09/RopeWalker.cs	
@@ -16,14 +16,18 @@
     internal class RopeWalker
     {
         private readonly VirtualPoint HeadLocation = new();
-        private VirtualPoint LastHeadLocation = new();
-
         private VirtualPoint TailLocation = new();
 
         private List<string> TailVistedLocations = new();
 
-        internal int ProcessMovement(string[] movements)
+        internal int ProcessMovement(string[] movements, int ropeLength)
         {
+            VirtualPoint[] rope = new VirtualPoint[ropeLength];
+            for (int ropeIndex = 0; ropeIndex < rope.Length; ropeIndex++)
+            {
+                rope[ropeIndex] = new VirtualPoint();
+            }
+
             // add the start position
             TailVistedLocations.Add($"0,0");
 
@@ -34,27 +38,32 @@
 
                 for (int movement = 0; movement < amountToMove; movement++)
                 {
-                    // set the last pos before moving
-                    LastHeadLocation.X = HeadLocation.X;
-                    LastHeadLocation.Y = HeadLocation.Y;
 
                     // do the actual move
                     switch (direction)
                     {
-                        case 'U': HeadLocation.Translate(0, 1); break;
-                        case 'D': HeadLocation.Translate(0, -1); break;
-                        case 'R': HeadLocation.Translate(1, 0); break;
-                        case 'L': HeadLocation.Translate(-1, 0); break;
+                        case 'U': rope[0].Translate(0, 1); break;
+                        case 'D': rope[0].Translate(0, -1); break;
+                        case 'R': rope[0].Translate(1, 0); break;
+                        case 'L': rope[0].Translate(-1, 0); break;
                     }
 
-                    // check if the tail is touching
-                    if (!IsTailTouchingHead(HeadLocation, TailLocation))
+                    for (int ropeIndex = 1; ropeIndex < rope.Length; ropeIndex++)
                     {
-                        TailLocation.Translate(Math.Sign(HeadLocation.X - TailLocation.X), Math.Sign(HeadLocation.Y - TailLocation.Y));
+                        if (!IsTailTouchingHead(rope[ropeIndex - 1], rope[ropeIndex]))
+                        {
+                            rope[ropeIndex].Translate(Math.Sign(rope[ropeIndex - 1].X - rope[ropeIndex].X), Math.Sign(rope[ropeIndex - 1].Y - rope[ropeIndex].Y));
 
-                        // add the new position to the list of visited positions
-                        TailVistedLocations.Add($"{TailLocation.X},{TailLocation.Y}");
+                            // add the new position to the list of visited positions
+                            
+                            continue;
+                        }
+
+                        // if not touching nothing has changed so stop with checking
+                        break;
                     }
+
+                    TailVistedLocations.Add($"{rope[^1].X},{rope[^1].Y}");
                 }
             }