From e6c44739347780015fff8f3ca5d75072e7cf8414 Mon Sep 17 00:00:00 2001
From: Parnic <github@parnic.com>
Date: Mon, 2 Dec 2024 08:20:03 -0600
Subject: [PATCH] Day 2

This is ugly, but the problem is small enough that it works just fine.
---
 src/02.cs | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 src/02.cs

diff --git a/src/02.cs b/src/02.cs
new file mode 100644
index 0000000..5bbfcf9
--- /dev/null
+++ b/src/02.cs
@@ -0,0 +1,88 @@
+namespace aoc2024;
+
+internal class Day02 : Day
+{
+    private List<List<int>> nums = [];
+    internal override void Parse()
+    {
+        var lines = Util.Parsing.ReadAllLines($"{GetDay()}");
+        foreach (var line in lines)
+        {
+            var split = line.Split(' ', StringSplitOptions.RemoveEmptyEntries);
+            List<int> list = [];
+            split.ForEach(n => list.Add(int.Parse(n)));
+            nums.Add(list);
+        }
+    }
+
+    internal override string Part1()
+    {
+        int numSafe = 0;
+        foreach (var list in nums)
+        {
+            bool isValid = true;
+            bool dir = list[1] > list[0];
+            for (int i = 1; i < list.Count; i++)
+            {
+                var diff = list[i] - list[i - 1];
+                if (Math.Abs(diff) > 3 || dir != list[i] > list[i - 1] || list[i] == list[i - 1])
+                {
+                    isValid = false;
+                    break;
+                }
+            }
+
+            if (isValid)
+            {
+                numSafe++;
+            }
+        }
+
+        return $"Safe reports: <+white>{numSafe}";
+    }
+
+    internal override string Part2()
+    {
+        bool IsValidFunc(List<int> list)
+        {
+            bool dir = list[1] > list[0];
+            for (int i = 1; i < list.Count; i++)
+            {
+                var diff = list[i] - list[i - 1];
+                if (Math.Abs(diff) > 3 || dir != list[i] > list[i - 1] || list[i] == list[i - 1])
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
+        int numSafe = 0;
+        foreach (var list in nums)
+        {
+            bool isValid = IsValidFunc(list);
+            if (!isValid)
+            {
+                // super crappy way to do this, but the input set is small enough for it to work.
+                for (int i = 0; i < list.Count; i++)
+                {
+                    var list2 = new List<int>(list);
+                    list2.RemoveAt(i);
+                    if (IsValidFunc(list2))
+                    {
+                        isValid = true;
+                        break;
+                    }
+                }
+            }
+
+            if (isValid)
+            {
+                numSafe++;
+            }
+        }
+
+        return $"Problem-dampener safe reports: <+white>{numSafe}";
+    }
+}