sum2 in n*2

gistfile1.txt

  def sum2 choices, result
    arrays = []
    choices.each_with_index {|i, index|
      choices.each_with_index {|j, index2|
        break if index == index2
         arrays << [i, j] if i + j == result
        }
      }
    arrays
  end
  
  def sum2 choices, result 
  complements = choices.inject({}) { |agg, choice|
    agg[result - choice] = choice unless agg.keys.include?(choice)
    agg
  }

  choices.map { |choice|
    if !complements[choice].nil?
      [choice, complements[choice]]
    end
    }.compact
end

# p sum2 [4, 5, 7, 6, 2, 1], 3 # [[1, 2]]
# p sum2 [-1, 0, 1, 2], 1 # [[1, 0], [2, -1]] 
p sum2 [-1, 0, 1, 2], 0 # [[1, 0], [2, -1]] 

big = 10
# p sum2((-big..big), 0)

def sum2 choices, result
complements = choices.inject({}) { |agg, choice|
agg[result - choice] = choice unless agg.keys.include?(choice)
agg
}

choices.map { |choice|
if !complements[choice].nil?
[choice, complements[choice]]
end
}.compact
end

p sum2 [4, 5, 7, 6, 2, 1], 3 # [[1, 2]]

p sum2 [-1, 0, 1, 2], 1 # [[1, 0], [2, -1]]

p sum2 [-1, 0, 1, 2], 0 # [[1, 0], [2, -1]]

big = 10

p sum2((-big..big), 0)