fibonacci

I'm trying to solve questions from Project Euler in Ruby one-liners, and I'm curious if there's a more elegant solution for question two : 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. Here is my one line solution in Ruby: (1..32).inject([0,1]) {|arr, i| (arr << arr[-1] + arr[-2] if arr[-1] + arr[-2] <= 4000000) || arr}.inject(0) {

def mystery(n): a, b = 0, 1 while a < n: print (a) a, b = b, a + b If someone could give me a line by line explanation of this code, as also inform of why it will not run, and what extra code needs to be added. def mystery(n): # define a function named "mystery", that takes one argument called "n" a, b = 0, 1 # make a variable named "a" and set it to 0; make a variable named "b" and set it to 1 while a < n: # as long as "a" is smaller than "n" print (a) # display the value contained in "a" on the screen a, b = b, a + b # set "b" to the sum of "a" and "b"; set "a" to the old value of "b"

This question already has an answer here: Multiple assignment and evaluation order in Python 8 answers I'm new to python so I want to ask you a question.. Previously while I was writing a fibonacci function I tryed to replace a, b = b, a+b with a = b b = a + b Believing that it was the same thing but I noted that the output is different (and wrong) Shouldn't these two codes do the same thing? Here it is the full code: #!/usr/bin/env python # -*- coding: utf-8 -*- def main(args): fibonacci(1000) return 0 def fibonacci(n): a, b = 0, 1 while b < n: print b, a, b = b, a+b # if I comment this and

I'm kind of beginner in python. I was looking at one the types to make a fibonacci function, def fib(n): a=0 b=1 while a<n: print a a,b=b,a+b and I saw the a,b=b,a+b declaration. So, I thought a=b and b=a+b were the same to a,b=a,b+a, so I changed the function for it to be like this: def fib(n): a=0 b=1 while a<n: print a a=b b=a+b and I thought it would be right, but when I executed the program, I got a different output. Can someone explain to me the difference between those two types of declaration? Thanks, anyway. b, a+b creates a tuple containing those two values. Then a, b = ... unpacks

I defined a function to return Fibonacci stream as follows: def fib:Stream[Int] = { Stream.cons(1, Stream.cons(2, (fib zip fib.tail) map {case (x, y) => println("%s + %s".format(x, y)); x + y})) } The functions work ok but it looks inefficient (see the output below) scala> fib take 5 foreach println 1 2 1 + 2 3 1 + 2 2 + 3 5 1 + 2 1 + 2 2 + 3 3 + 5 8 So, it looks like the function calculates the n-th fibonacci number from the very beginning. Is it correct? How would you fix it? oxbow_lakes That is because you have used a def . Try using a val : lazy val fib: Stream[Int] = 1 #:: 2 #:: (fib zip