Better way for calculating project euler's 2nd problem Fibonacci sequence)
- by firephil
object Problem_2 extends App {
def fibLoop():Long =
{
var x = 1L
var y = 2L
var sum = 0L
var swap = 0L
while(x < 4000000)
{
if(x % 2 ==0) sum +=x
swap = x
x = y
y = swap + x
}
sum
}
def fib:Int = {
lazy val fs: Stream[Int] = 0 #:: 1 #:: fs.zip(fs.tail).map(p => p._1 + p._2)
fs.view.takeWhile(_ <= 4000000).filter(_ % 2 == 0).sum
}
val t1 = System.nanoTime()
val res = fibLoop
val t2 = (System.nanoTime() - t1 )/1000
println(s"The result is: $res time taken $t2 ms ")
}
Is there a better functional way for calculating the fibonaci sequence and taking the sum of the the even values below 4million ? (projecteuler.net - problem 2)
The imperative method is 1000x faster ?
