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.
We are given our bounds in the problem,
1..4000000 , and we are to find and sum every even fibonacci number inside the given bounds.
To start off, we should define a function to generate a list of fibonacci numbers. I opted for a recursive function, but this could easily be achieved using simple loops as well.
def fib(nums, maxNum): if not (nums[-1] >= maxNum): nums.append(nums[-1] + nums[-2]) fib(nums, maxNum) return nums
With that function defined, the rest of the problem is simply iterating through the array of fibonacci numbers, testing if they are even, and adding them to a sum value.
def main(): nums = [1,2,3] maxNum = 4000000 nums = fib(nums, maxNum) fibSum = 0 for num in nums: if (num % 2) == 0: fibSum += num print(fibSum) def fib(nums, maxNum): if not (nums[-1] >= maxNum): nums.append(nums[-1] + nums[-2]) fib(nums, maxNum) return nums if __name__ == "__main__": main()