From 6e433fcf3d25b0d01282e41216704a42f3ad4ee8 Mon Sep 17 00:00:00 2001
From: Eveldee <eveldee0680@live.fr>
Date: Fri, 24 Jan 2025 10:19:12 +0100
Subject: [PATCH] Add day 11

---
 Days/Day11.cs    | 127 +++++++++++++++++++++++++++++++++++++++++++++++
 Inputs/Day11.txt |   1 +
 2 files changed, 128 insertions(+)
 create mode 100644 Days/Day11.cs
 create mode 100644 Inputs/Day11.txt

diff --git a/Days/Day11.cs b/Days/Day11.cs
new file mode 100644
index 0000000..1fc0930
--- /dev/null
+++ b/Days/Day11.cs
@@ -0,0 +1,127 @@
+using System.Collections.Frozen;
+using System.Numerics;
+using Spectre.Console;
+
+namespace AdventOfCode.Days;
+
+public class Day11 : Day
+{
+    public override int Number => 11;
+    public override string Name => "Plutonian Pebbles";
+
+    private const int BlinkIterations = 25;
+
+    public override void RunPart1(bool display = true)
+    {
+        var stones = ParseStones();
+
+        for (var iteration = 0; iteration < BlinkIterations; iteration++)
+        {
+            var index = 0;
+
+            while (index < stones.Count)
+            {
+                var stone = stones[index];
+                var stoneString = stone.ToString();
+
+                if (stone is 0)
+                {
+                    stones[index] = 1;
+                }
+                else if (stoneString.Length % 2 == 0)
+                {
+                    var splitIndex = stoneString.Length / 2;
+
+                    var leftStone = long.Parse(stoneString[..splitIndex]);
+                    var rightStone = long.Parse(stoneString[splitIndex..]);
+
+                    stones[index] = leftStone;
+                    stones.Insert(index + 1, rightStone);
+
+                    index++;
+                }
+                else
+                {
+                    stones[index] = stone * 2024;
+                }
+
+                index++;
+            }
+        }
+
+        if (display)
+        {
+            AnsiConsole.MarkupLine($"[green]Number of stones after blinking {BlinkIterations} times: [yellow]{stones.Count}[/][/]");
+        }
+    }
+
+    public override void RunPart2(bool display = true)
+    {
+        var stones = ParseStones().ToDictionary(s => s, _ => 1L);
+
+        for (var iteration = 0; iteration < (BlinkIterations * 3); iteration++)
+        {
+            var stonesToIterate = stones.ToList();
+
+            foreach (var (stone, count) in stonesToIterate)
+            {
+                var stoneString = stone.ToString();
+
+                if (stone is 0)
+                {
+                    SafeAdd(stones, 1, count);
+                }
+                else if (stoneString.Length % 2 == 0)
+                {
+                    var splitIndex = stoneString.Length / 2;
+
+                    var leftStone = long.Parse(stoneString[..splitIndex]);
+                    var rightStone = long.Parse(stoneString[splitIndex..]);
+
+                    SafeAdd(stones, leftStone, count);
+                    SafeAdd(stones, rightStone, count);
+                }
+                else
+                {
+                    SafeAdd(stones, stone * 2024, count);
+
+                }
+
+                SafeAdd(stones, stone, -count);
+            }
+        }
+
+        var stonesCount = stones.Sum(p => p.Value);
+
+        if (display)
+        {
+            AnsiConsole.MarkupLine($"[green]Number of stones after blinking {BlinkIterations} times: [yellow]{stonesCount}[/][/]");
+        }
+    }
+
+    private List<long> ParseStones()
+    {
+        var stones = new List<long>();
+
+        var span = Input.AsSpan();
+
+        foreach (var stoneRange in span.Split(' '))
+        {
+            stones.Add(long.Parse(span[stoneRange]));
+        }
+
+        return stones;
+    }
+
+    private void SafeAdd(Dictionary<long, long> dictionary, long key, long valueToAdd)
+    {
+        if (dictionary.TryGetValue(key, out var currentValue))
+        {
+            dictionary[key] = currentValue + valueToAdd;
+        }
+        else
+        {
+            dictionary[key] = valueToAdd;
+        }
+    }
+}
\ No newline at end of file
diff --git a/Inputs/Day11.txt b/Inputs/Day11.txt
new file mode 100644
index 0000000..4959fe9
--- /dev/null
+++ b/Inputs/Day11.txt
@@ -0,0 +1 @@
+0 7 6618216 26481 885 42 202642 8791
\ No newline at end of file