Merge branch 'master' of https://github.com/StevenH237/CSharp.Nixill

CSharp.Nixill/src/Collections/INavigable/AVLTree/AVLTreeDictionary.cs

@@ -142,7 +142,7 @@ public AVLTreeDictionary(IEnumerable<KeyValuePair<K, V>> elems, IComparer<K> com
   public AVLTreeDictionary(IEnumerable<KeyValuePair<K, V>> elems, Comparison<K> comparer)
   {
     this.KeyComparer = comparer;
-    BackingSet = new AVLTreeSet<KeyValuePair<K, V>>((left, right) => KeyComparer(left.Key, right.Key));
+    BackingSet = new AVLTreeSet<KeyValuePair<K, V>>(elems, (left, right) => KeyComparer(left.Key, right.Key));
   }
   #endregion
 

CSharp.Nixill/src/Utils/Extensions/CollectionExtensions.cs

@@ -93,6 +93,18 @@ public static V GetOrSet<K, V>(this IDictionary<K, V> dictionary, K key, Func<V>
     return returnValue;
   }
 
+  /// <summary>
+  ///   Returns an int enumerable over the indices of a collection (from
+  ///   0, inclusive, to the collection's size, exclusive).
+  /// </summary>
+  /// <typeparam name="T">
+  ///   The type of elements in the collection.
+  /// </typeparam>
+  /// <param name="input">The collection.</param>
+  /// <returns>The enumerable.</returns>
+  public static IEnumerable<int> Indices<T>(this ICollection<T> input)
+    => Enumerable.Range(0, input.Count);
+
   /// <summary>
   ///   Removes the first item from an <see cref="IList{T}"/> and returns it.
   /// </summary>

CSharp.Nixill/src/Utils/Extensions/SetExtensions.cs

@@ -449,6 +449,23 @@ public static IEnumerable<TResult> Product<TLeft, TRight, TResult>(this IEnumera
   public static IEnumerable<(TLeft, TRight)> Product<TLeft, TRight>(this IEnumerable<TLeft> left, IEnumerable<TRight> right) =>
     left.Join(right, x => 1, y => 1, (left, right) => (left, right));
 
+  /// <summary>
+  ///   For each element in a sequence, returns that element paired with
+  ///   the remainder of the sequence after it.
+  /// </summary>
+  /// <typeparam name="T">
+  ///   The type of elements in the sequence.
+  /// </typeparam>
+  /// <param name="input">The sequence.</param>
+  /// <returns>The elements and remainders.</returns>
+  public static IEnumerable<(T, IEnumerable<T>)> Remainders<T>(this IEnumerable<T> input)
+  {
+    T[] array = input.ToArray();
+
+    foreach (int index in array.Indices())
+      yield return (array[index], array[(index + 1)..]);
+  }
+
   /// <summary>
   ///   Returns all elements in one sequence or the other, but not both.
   /// </summary>