Created
December 8, 2011 23:14
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By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.
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| vals = [0, 1] | |
| 34.times do | |
| val = vals[-1] + vals[-2] | |
| vals.push(val) if val < 4000000 | |
| end | |
| vals.select{|item| item % 2 == 0 }.inject(:+) |
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require 'matrix'
sum = 0
for n in (1 .. 33)
fib = (Matrix[[1,1],[1,0]] ** (n-1))[0,0]
sum += fib if (fib < 4000000) && (fib % 2 == 0)
end
sum