indyrb interview problem

counted_recurring_elements

def counted_recurring_elements_in(array)
  counts_by_number = array.inject({}) do |memo, element|   
    memo[element] = memo[element].to_i  + 1    # I like this trick but I wish it didn't rely on knowing nil.to_i == 1
    memo 
  end

  recurring_counts_by_number = counts_by_number.select do |number, count|
    count > 1 
  end

  recurring_counts_by_number
end

nil.to_i == 0*

I believe this does the same thing while removing the hack you don't like.

counts_by_number = array.inject(Hash.new(0)) do |memo, element|
    memo[element] += 1
    memo
end