Data commit

Task/Perfect-shuffle/C-sharp/perfect-shuffle.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+public static class PerfectShuffle
+{
+    static void Main()
+    {
+        foreach (int input in new [] {8, 24, 52, 100, 1020, 1024, 10000}) {
+            int[] numbers = Enumerable.Range(1, input).ToArray();
+            Console.WriteLine($"{input} cards: {ShuffleThrough(numbers).Count()}");
+        }
+
+        IEnumerable<T[]> ShuffleThrough<T>(T[] original) {
+            T[] copy = (T[])original.Clone();
+            do {
+                yield return copy = Shuffle(copy);
+            } while (!Enumerable.SequenceEqual(original, copy));
+        }
+    }
+
+    public static T[] Shuffle<T>(T[] array) {
+        if (array.Length % 2 != 0) throw new ArgumentException("Length must be even.");
+        int half = array.Length / 2;
+        T[] result = new T[array.Length];
+        for (int t = 0, l = 0, r = half; l < half; t+=2, l++, r++) {
+            result[t] = array[l];
+            result[t+1] = array[r];
+        }
+        return result;
+    }
+
+}