Added recursive_multiply.cpp; Problem no 8.5

Author: ravi688

recursive_multiply.cpp

@@ -0,0 +1,66 @@
+#include <iostream>
+
+// Solution no 1
+static std::size_t multiply1(std::size_t n1, std::size_t n2)
+{
+	if(n2 == 1)
+		return n1;
+	return multiply1(n1, n2 - 1) + n1;
+}
+
+// Solution no 2
+static std::size_t multiply2(std::size_t n1, std::size_t n2)
+{
+	if(n2 == 1)
+		return n1;
+	auto halfn2 = n2 >> 1;
+	return (multiply2(n1, halfn2) << 1) + ((n2 & 1) ? n1 : 0);
+}
+
+struct Solution1
+{
+	std::size_t operator()(std::size_t n1, std::size_t n2)
+	{
+		return multiply1(n1, n2);
+	}
+};
+
+struct Solution2
+{
+	std::size_t operator()(std::size_t n1, std::size_t n2)
+	{
+		return multiply2(n1, n2);
+	}
+};
+
+template<typename Sol>
+static void runMultiply(std::size_t n1, std::size_t n2)
+{
+	std::cout << "Input: n1 = " << n1 << ", n2 = " << n2 << "\n";
+	std::size_t result = Sol { } (n1, n2);
+	std::cout << "Output: " << result << "\n";
+}
+
+static void run(std::size_t n1, std::size_t n2)
+{
+	static std::size_t runCount = 0;
+	std::cout << "--------RUN: " << runCount << " --------\n";
+	++runCount;
+	std::cout << "**Solution no 1**\n";
+	runMultiply<Solution1>(n1, n2);
+	std::cout << "**Solution no 2**\n";
+	runMultiply<Solution2>(n1, n2);
+}
+
+int main()
+{
+	run(10, 30);
+	run(20, 23);
+	run(12, 11);
+	run(1, 1);
+	run(2, 3);
+	run(4, 4);
+	run(8, 4);
+	run(3, 5);
+	return 0;
+}