factorial.cpp (#561)

* Create factorial.cpp

* Update and rename Math/factorial.cpp to math/factorial.cpp

* Update factorial.cpp

* Update factorial.cpp

math/factorial.cpp

+// C++ program to find factorial of given number
+#include<iostream>
+
+// function to find factorial of given number
+unsigned int factorial(unsigned int n) {
+    if (n == 0)
+        return 1;
+    return n * factorial(n - 1);
+}
+
+// Driver code
+int main() {
+    int num = 5;
+    std::cout << "Factorial of " << num << " is " << factorial(num)
+              << std::endl;
+    return 0;
+}