Problem0002.py

Enonce = """
Even Fibonacci numbers
Problem 2 
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.
"""

# Iterator style
class Fibonacci:
  def __init__(self, size=None, highest_value=None):
    self.previous = [0, 1]
    self.index = size
    self.highest_value = highest_value

  def __iter__(self):
    return self

  def __next__(self):
    if self.index is not None:
        if self.index == 0 :
            raise StopIteration
        self.index = self.index - 1
    value = self.previous.pop(0) + self.previous[0]
    self.previous.append(value)
    if self.highest_value is not None:
        if self.highest_value < value :
            raise StopIteration
    return value


# Iterable style (large memory)
def fibonacci(size):
    if size == 1:
        return [1]
    elif size == 2:
        return [1, 2]
    else:
        fibo = fibonacci(size-1)
        fibo.append(fibo[-2]+fibo[-1])
        return fibo
    
def main():
    print(40*"=")
    print(Enonce)
    print(40*"-")

    Solution = 0
    highest = 4_000_000
    print(f"Even Fibonacci values lower than {highest} :") # f"abc{toto}" == "abc{}".format(toto)
    for v in Fibonacci(highest_value=highest):
        if v%2 == 0:
            print(v)
            Solution += v
    
    print(40*"-")
    print("Solution = {}".format(Solution))
    print(40*"=")

if __name__ == "__main__":
    # execute only if run as a script
    main()