Project Euler Problem 2

euler2.rb

# Project Euler 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.

# The longer way (so you can see what is going on)
# We put the even valued terms into an array and then use
# inject to add all the items together giving the sum
# of the even-valued terms
first = 0
second = 1
i = 0
sequence = []

while i <= 4000000
  i = first + second
  sequence << i if i % 2 == 0
  # puts sequence
  first = second
  second = i
end
puts "The sum of the even valued terms is #{sequence.inject(:+)}"


# The shorter way
# sum the even valued terms as we move
# through the loop
first = 0
second = 1
i = 0
sum = 0

while i <= 4000000
  i = first + second
  sum += i if i % 2 == 0
  first = second
  second = i
end
puts sum