Day 1

src/Util/Extensions.cs

@@ -0,0 +1,49 @@
+namespace aoc2024.Util;
+
+public static class Extensions
+{
+    public static bool IsDigit(this char c) => c >= '0' && c <= '9';
+
+    public static void AddUnique<T>(this ICollection<T> list, T elem)
+    {
+        if (!list.Contains(elem))
+        {
+            list.Add(elem);
+        }
+    }
+
+    public static int IndexOf<T>(this ICollection<T> list, T elem) where T : IEquatable<T>
+    {
+        for (int idx = 0; idx < list.Count; idx++)
+        {
+            if (list.ElementAt(idx).Equals(elem))
+            {
+                return idx;
+            }
+        }
+
+        return -1;
+    }
+
+    public static string ReplaceFirst(this string str, char ch, char replace)
+    {
+        for (int i = 0; i < str.Length; i++)
+        {
+            if (str[i] == ch)
+            {
+                return str.ReplaceAt(i, replace);
+            }
+        }
+
+        return str;
+    }
+
+    public static string ReplaceAt(this string str, int index, char replace)
+    {
+        return str[..index] + replace + str[(index + 1)..];
+    }
+
+    public static bool SequenceEquals<T>(this T[,] a, T[,] b) => a.Rank == b.Rank
+                                                                 && Enumerable.Range(0, a.Rank).All(d=> a.GetLength(d) == b.GetLength(d))
+                                                                 && a.Cast<T>().SequenceEqual(b.Cast<T>());
+}