two_sum_problem.rb

# check if there is two integers which sum up to the targeted sum
def two_sum(arr, target)
  arr.sort!
  size = arr.size
  i, j = 0, size-1
  count = 0
  while(i<j) do
    sum = arr[i] + arr[j]
    if sum == target
    	count += 1
    	i+=1
    elsif sum < target
    	i += 1
    else
    	j -= 1
    end
  end
  count
end
puts two_sum([0,1,2,3,4,5], 5)