add Fisher-Yates (Knuth) shuffling algorithm

Shuffle/Shuffle.cpp

@@ -0,0 +1,46 @@
+/*
+ * Shuffling Algorithms (C++ implementation)
+ *
+ * Shuffle randomize a given array. Here shuffle means that every permutation
+ * of array element should equally likely.
+ * It uses Fisher-Yates (Knuth) shuffling algorithm.
+ *
+ * e.g. shuffle a deck of cards
+ *
+ * Fisher–Yates shuffle Algorithm works in O(n) time complexity.
+ * The assumption here is, we are given a function rand() that generates
+ * random number in O(1) time.
+ */
+
+#include <iostream>
+
+/**
+ * Shuffle Array Template Function
+ * @param arr actual array to sort
+ * @param len size of array
+ */
+template <typename T>
+void Shuffle(T arr[], int len)
+{
+     // use current time as seed for random generator
+    std::srand(std::time(nullptr));
+    for (int i = 0; i < len; i++) {
+        int r = rand() % (i + 1);
+        std::swap(arr[i], arr[r]);
+    }
+}
+
+/* Main Driver Function */
+int main()
+{
+    int arr[] = {229, 79, 46, 12, 58, 31, 34, 67, 89, 12, 67, 2};
+    int len = sizeof(arr) / sizeof(arr[0]);
+
+    Shuffle<int>(arr, len);
+
+    for (int a: arr)
+        std::cout << a << " ";
+    std::cout << "\n";
+
+    return 0;
+}