Added cpp for Problem 2

ProjectEuler/C++/Problem2.cpp

@@ -0,0 +1,43 @@
+//ProjectEuler/C++/Problem2.cpp
+//Matthew Ellison
+// Created: 9-28-18
+//Modified: 9-28-18
+//The sum of the even Fibonacci numbers less than 4,000,000
+
+
+#include <iostream>
+#include <vector>
+#include <chrono>
+
+
+int main(){
+	unsigned long fullSum = 2;	//Holds the sum of all the numbers
+	std::vector<unsigned long> fib = {1, 1};	//Holds the Fibonacci numbers
+	unsigned long nextFib = 2;	//Holds the next Fibonacci number
+
+	std::chrono::high_resolution_clock::time_point startTime = std::chrono::high_resolution_clock::now();	//Start the timer
+	while(nextFib < 4000000){
+		//If it is an even number add it to the sum
+		if(nextFib % 2){
+			fullSum += nextFib;
+		}
+		//Move all the fib numbers down and calculate the next one
+		fib.at(0) = fib.at(1);
+		fib.at(1) = nextFib;
+		nextFib = fib.at(1) + fib.at(0);
+		//You could do this keeping all the fib numbers and sum at the end,
+		//but this way will be faster because you are only handling every number twice
+		//and you don't have to expand the vector
+	}
+	//Calculate the time needed for the algorithm
+	std::chrono::high_resolution_clock::time_point endTime = std::chrono::high_resolution_clock::now();	//End the timer
+	std::chrono::high_resolution_clock::duration dur = std::chrono::duration_cast<std::chrono::nanoseconds>(endTime - startTime);
+
+	//Print the resultss
+	std::cout << "The sum of the even Fibonacci numbers less than 4,000,000 is " << fullSum
+			<< "\nIt took " << dur.count() << " nanoseconds to run this algorithm" << std::endl;
+
+	//Pause before ending
+	std::cin.get();
+	return 0;
+}