Determine the longest contiguous sub-array consisting of no more than two unique characters within an array

findBiSlice.rb

# Determine the longest contiguous sub-array consisting of
# no more than two unique characters within an array
#
# @author Cam Crews
# @see https://codefights.com/challenge/n75eG9MuhDzejuCyp/main
#
# @param a [Array] array to scan
# @return [Integer] length of subarray
def findBiSlice a
  # q - queue, our current scan region
  q = []
  # m - maximum count
  # b - previous count of consecutive characters
  # c - current count of consecutive characters
  m = b = c = 0
  a.each do |v| 
    # if we have a new element not in our queue
    if (q & [v]).empty?
      # remove the first queue element (if queue is full)
      q.shift if q.size > 1
      # and add the new element to the back of the queue
      q.push v
      # our current count becomes our previous count
      b = c
      # and we reset the current count to 1
      c = 1
    else 
      # else, we found an element already in the queue
      # check whether the incoming character is
      # different from the most recent into our queue
      if v != q[-1]
        # switch positions in the queue, if so
        q = q.rotate
        # save out current count to previous
        b += c
        # and reset current count
        c = 0
      end
      c += 1
    end
    # update maximum, if maximum exceeded
    m = b+c if b+c > m
  end
  m
end