CODEWITHSUNDEEP
ruby
megas
megas

Reputation: 21791

How to make sequence from specific number?

How to make sequence from the beginning of square number and then adding it to the previous result?

7 => 49, 56, 63, ...

def make_sequence(number)
  lambda { number*number ??? }
end

num = make_sequence(7)
num.call #=> 49
num.call #=> 56
...

Upvotes: 3

Views: 81

Answers (3)

tokland
tokland

Reputation: 67850

Following your initial idea using closures I'd write:

def make_sequence(n)
  x = n**2 - n
  lambda { x += n }
end

num = make_sequence(7)
p num.call #=> 49
p num.call #=> 56

Upvotes: 3

halfelf
halfelf

Reputation: 10107

A Fiber version:

def make_sequence(num)
  inc = num
  num = num*num
  Fiber.new do
    loop do
      Fiber.yield(num)
      num += inc
    end
  end
end

a = make_sequence(7)
p a.resume  #=> 49
p a.resume  #=> 56
p a.resume  #=> 63
...

Upvotes: 2

levinalex
levinalex

Reputation: 5949

use Enumerator

def make_sequence(start)
  pos = start**2
  Enumerator.new do |y|
    loop do
      y.yield(pos)
      pos += start
    end
  end
end

seq = make_sequence(7)
seq.next   #=> 49
seq.next   #=> 56

...

Upvotes: 2

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