Module: CompSci::Fibonacci

Defined in:
lib/compsci/fib.rb

Class Method Summary collapse

Class Method Details

.cache_iterative(n) ⇒ Object 



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# File 'lib/compsci/fib.rb', line 13

def self.cache_iterative(n)
  cache = [0, 1]
  2.upto(n) { |i| cache[i] = cache[i-1] + cache[i-2] }
  cache[n]
end

.cache_recursive(n, cache = {}) ⇒ Object 



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# File 'lib/compsci/fib.rb', line 8

def self.cache_recursive(n, cache = {})
  return n if n < 2
  cache[n] ||= cache_recursive(n-1, cache) + cache_recursive(n-2, cache)
end

.classic(n) ⇒ Object 



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# File 'lib/compsci/fib.rb', line 4

def self.classic(n)
  n < 2 ? n : classic(n-1) + classic(n-2)
end

.dynamic(n) ⇒ Object 



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# File 'lib/compsci/fib.rb', line 19

def self.dynamic(n)
  a, b = 0, 1
  (n-1).times { a, b = b, a+b }
  b
end