2018 day 1 and 2

AOC.Common/Extensions.cs

@@ -122,4 +122,10 @@ public static class Extensions
     public static IEnumerable<KeyValuePair<TKey, TValue>> WhereValue<TKey, TValue>(
         this IEnumerable<KeyValuePair<TKey, TValue>> source, Func<TValue, bool> func) =>
         source.Where(pair => func(pair.Value));
+
+    public static int HammingDistance(this string s1, string other)
+    {
+        if (s1.Length != other.Length) throw new("Strings must be equal length.");
+        return s1.Zip(other).Count(s => s.First != s.Second);
+    }
 }

AOC.Test/Test2018.cs

@@ -6,7 +6,8 @@ namespace AOC.Test;
 public class Test2018
 {
     [DataTestMethod]
-    [DataRow(typeof(Day01), "", "")]
+    [DataRow(typeof(Day01), "582", "488")]
+    [DataRow(typeof(Day02), "5166", "cypueihajytordkgzxfqplbwn")]
     public void CheckAllDays(Type dayType, string part1, string part2)
     {
         Common.CheckDay(dayType, part1, part2);

AOC2018/Day01.cs

@@ -5,7 +5,7 @@ namespace AOC2018;
 /// </summary>
 public sealed class Day01 : Day
 {
-    public Day01() : base(2018, 1, "Puzzle Name")
+    public Day01() : base(2018, 1, "Chronal Calibration")
     {
     }
     
@@ -13,7 +13,12 @@ public sealed class Day01 : Day
     {
     }
 
-    public override object Part1() => "";
+    public override object Part1() => Input.Select(int.Parse).Sum();
 
-    public override object Part2() => "";
+    public override object Part2()
+    {
+        var frequencies = new HashSet<int>();
+        var freq = 0;
+        return Input.Select(int.Parse).Repeat().Any(f => !frequencies.Add(freq += f)) ? freq : 0;
+    }
 }

AOC2018/Day02.cs

@@ -5,15 +5,34 @@ namespace AOC2018;
 /// </summary>
 public sealed class Day02 : Day
 {
-    public Day02() : base(2018, 2, "Puzzle Name")
+    public Day02() : base(2018, 2, "Inventory Management System")
     {
     }
-    
+
     public override void ProcessInput()
     {
     }
 
-    public override object Part1() => "";
+    private static bool HasNChars(string line, int count)
+    {
+        for (var i = 'a'; i <= 'z'; i++)
+            if (line.Count(c => c == i) == count)
+                return true;
 
-    public override object Part2() => "";
-}
+        return false;
+    }
+
+    public override object Part1() =>
+        Input.Count(l => HasNChars(l, 2)) * Input.Count(l => HasNChars(l, 3));
+
+    public override object Part2()
+    {
+        var input = Input.ToImmutableList();
+
+        foreach (var id1 in input)
+        foreach (var id2 in input.Where(line2 => id1.HammingDistance(line2) == 1))
+            return id1.Remove(id1.Zip(id2).Indexed().First(i => i.Value.First != i.Value.Second).Key, 1);
+
+        throw new("Correct IDs not found");
+    }
+}