Solution in Python for Project Euler's problem #2

Problem 2 - Even Fibonacci numbers

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.

Python solution

it is very fast even for numbers up to 1e200

def fibsum(maximum):
    fib1 = 0
    fib2 = 1
    sum = 0
    while fib2 < maximum:
        aux = fib2
        fib2 += fib1
        fib1 = aux
        if fib2 & 1 == 0:
            sum += fib2
    return sum
        
print fibsum(int(4e6))