Euler 2. Even Fibonacci Numbers

Problem Statement

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.

Solution

func Two() int {

	iterOne := 0
	iterTwo := 1
	currFib := 0
	maxFib := 4000000
	sum := 0
	for currFib < maxFib {
		// is currFib even
		if currFib%2 == 0 {
			sum += currFib
		}

		// Calculate nextFib
		currFib = iterOne + iterTwo
		iterOne = iterTwo
		iterTwo = currFib
	}

	return sum
}