19 lines
617 B
Haskell
19 lines
617 B
Haskell
-- 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.
|
|
|
|
fib :: Integer -> Integer
|
|
fib 0 = 0
|
|
fib 1 = 1
|
|
fib n = fib (n-1) + fib(n-2)
|
|
|
|
sumEvenFib :: Integer
|
|
sumEvenFib = sum $ filter even $ takeWhile (<=4000000) (map fib [0..])
|
|
|
|
main = do
|
|
let result = sumEvenFib
|
|
putStrLn $ "Project Euler, Problem 2\n"
|
|
++ "Answer: " ++ show result
|