Initial data commit

Task/Permutations/C-sharp/permutations-7.cs

@@ -0,0 +1,38 @@
+// Always returns the same array which is the one passed to the function
+public static IEnumerable<T[]> HeapsPermutations<T>(T[] array)
+{
+    var state = new int[array.Length];
+
+    yield return array;
+
+    for (var i = 0; i < array.Length;)
+    {
+        if (state[i] < i)
+        {
+            var left = i % 2 == 0 ? 0 : state[i];
+            var temp = array[left];
+            array[left] = array[i];
+            array[i] = temp;
+            yield return array;
+            state[i]++;
+            i = 1;
+        }
+        else
+        {
+            state[i] = 0;
+            i++;
+        }
+    }
+}
+
+// Returns a different array for each permutation
+public static IEnumerable<T[]> HeapsPermutationsWrapped<T>(IEnumerable<T> items)
+{
+    var array = items.ToArray();
+    return HeapsPermutations(array).Select(mutating =>
+        {
+            var arr = new T[array.Length];
+            Array.Copy(mutating, arr, array.Length);
+            return arr;
+        });
+}