package ProjectEuler;

/**
 * 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:
 * <p>
 * 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
 * <p>
 * By considering the terms in the Fibonacci sequence whose values do not exceed four million,
 * find the sum of the even-valued terms.
 * <p>
 * Link: https://projecteuler.net/problem=2
 */
public class Problem02 {
    public static void main(String[] args) {
        int[][] testNumbers = {
                {10, 10}, /* 2 + 8 == 10 */
                {15, 10}, /* 2 + 8 == 10 */
                {2, 2},
                {1, 0},
                {89, 44} /* 2 + 8 + 34 == 44 */
        };

        for (int[] ints : testNumbers) {
            assert solution1(ints[0]) == ints[1];
        }
    }

    private static int solution1(int n) {
        int sum = 0;
        int first = 1;
        int second = 2;
        while (second <= n) {
            if (second % 2 == 0) {
                sum += second;
            }
            int temp = first + second;
            first = second;
            second = temp;
        }
        return sum;
    }
}