Project Euler | Problem 2 | Even Fibonacci numbers

Problem Description :

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

Project Euler Problem 2

Concept :

In Fibonacci sequence, each Fibonacci term is a sum of previous two terms.

For example - F(N)=F(N-2)+F(N-1)

Java Program :

	package com.javamultiplex.projecteuler;
	import java.util.ArrayList;
	import java.util.List;
	/**
	*
	* @author Rohit Agarwal
	* @category Project Euler Problems
	* @problem Sum of even valued fibonacci terms below four million.
	*
	*/
	public class Problem2 {
	public static void main(String[] args) {
	int limit = 4000000; // 4 million
	long result = getSumOfEvenFibonacciSequence(limit);
	System.out.println("The sum of even valued terms of fibonacci sequence whose values do not exceed four million is : " + result);
	}
	private static long getSumOfEvenFibonacciSequence(int limit) {
	List<Integer> fib = new ArrayList<Integer>();
	// Default values of first two terms of fibonacci sequence is 1,1.
	fib.add(0, 1);
	fib.add(1, 1);
	int i = 1, temp, evenSum = 0;
	while (fib.get(i) <= limit) {
	i++;
	temp = getNextFibonacciTerm(fib, i);
	fib.add(i, temp);
	temp = fib.get(i);
	if (temp <= limit) {
	if (temp % 2 == 0) {
	evenSum += temp;
	}
	}
	}
	return evenSum;
	}
	private static int getNextFibonacciTerm(List<Integer> fib, int i) {
	// On adding previous 2 terms we can get next fibonacci term.
	int result = fib.get(i - 1) + fib.get(i - 2);
	return result;
	}
	}

view raw Problem2.java hosted with ❤ by GitHub

Output :

Output - Project Euler Problem 2

References :

https://projecteuler.net/problem=2

https://en.wikipedia.org/wiki/Fibonacci_number

https://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html

https://docs.oracle.com/javase/7/docs/api/java/util/List.html

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Tags : Project Euler Problem 2 Solution, Mathematics problems, Fibonacci numbers, Solution in Java, List, ArrayList, if statement, Dynamic programming, While loop.

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