Memory Puzzle solution

index.coffee

fs = require 'fs'

exports.countryIpCounter = (countryCode, cb) ->
  return cb() unless countryCode

  fs.readFile "#{__dirname}/../data/geo.txt", 'utf8', (err, data) ->
    if err then return cb err
    counter = 0
    data = data.toString()


    ###
    * Converting string to array is more costly so
    * I have changed algorithm to read string based on new line index
    *
    ###
    #data = data.toString().split '\n'

    # read substring form input string and parse each line
    loop
      index = data.indexOf('\n')
      line = data.substring(0, index)

      # exit from loop if all lines from string are parsed
      if line.length <= 0
        break

      # split and parse line iff only it exists
      if(line.length > 0)

        # existing logic
        line = line.split '\t'
        # GEO_FIELD_MIN, GEO_FIELD_MAX, GEO_FIELD_COUNTRY
        # line[0],       line[1],       line[3]
        if line[3] == countryCode then counter += +line[1] - +line[0]

      # remove parsed line from input
      data = data.replace(data.substring(0, index+1), "")
    cb null, counter

Solution to memory puzzle

Replace lib/index.coffee file code with this