eduardopoleo

def add_two(a, b)
  a.to_i + b.to_i
end


add_two(1, 1)


describe '#add_two' do
  context 'when I add two positive numbers' do

eduardopoleo

def produce_all(connection)
  count   = Outbox::Adapters::General::Messages.count
  batches = (count / batch_size.to_f).ceil

  batches.times do
    messages = Outbox::Adapters::General.order(:id).limit(batch_size).to_a

    grouped_messages = group_by_model_type(messages)

    while messages_to_process?(grouped_messages)

eduardopoleo

+----------------+------------------------+----------------+
| Solution       | Elapsed Real Time (s)* | Space(bytes)** |
+----------------+------------------------+----------------+
| Brute Force    | 168.1                  | N/A            |
| Hash           | 9.8                    | 6488           |
| Array          | 3.14                   | 1064           |
| Bit Array      | 6.2                    | 40             |
| Web Developer  | 9.7                    | 2128           |
+----------------+-----------------------------------------+

eduardopoleo

require 'objspace'

# "111...".to_i(2) A 128 "1"
big_int = 340282366920938463463374607431768211455 
ObjectSpace.memsize_of(big_int) # => 40

array = [true] * 128
ObjectSpace.memsize_of(big_int) # => 1064

hash = {"a" => true, "b" => true ...}

eduardopoleo

def unique_web_developer(s)
  s.split("").uniq.length == s.length
end

eduardopoleo

1) Performing the "|" operation 
100000
 11000
______
111000

2) Assinging the result to vector
vector = 111000

eduardopoleo

100000 -> shifted value result of (1 << 5)
 11000 -> characters with code 3 and 4 have been seen already.
______
000000 = 0

eduardopoleo

def unique_with_bit_array(s)
  vector = 0

  s.each_char do |char|
    code = char.ord

    if (vector & (1 << code)) > 0
      return false
    end

eduardopoleo

def unique_with_array(s)
  char_set = Array.new

  s.each_char do |char|
    code = char.ord

    return false if char_set[code]

    char_set[code] = true
  end

eduardopoleo

def unique_with_hash2(s)
  characters = {}

  s.each_char do |char|
    return false if characters[char]

    characters[char] = true
  end

  return true