Hun Jae Lee hunj

Studying for a Tech Interview Sucks, so Here's a Cheat Sheet to Help

This list is meant to be a both a quick guide and reference for further research into these topics. It's basically a summary of that comp sci course you never took or forgot about, so there's no way it can cover everything in depth. It also will be available as a gist on Github for everyone to edit and add to.

Data Structure Basics

###Array ####Definition:

Stores data elements based on an sequential, most commonly 0 based, index.
Based on tuples from set theory.

	## Found in: http://blog.firsthand.ca/2010/09/ruby-rdoc-example.html

	# * Style guide based on Rails documention
	module Namespace #:nodoc: don't document this

	# Generic Namespace exception class
	class NamespaceError < StandardError
	end

	# Raised when...

	def path_strip(input_file, domain, output_file)
	raise "domain must be string form" unless domain.is_a? String
	raise "invalid input file name" unless input_file.is_a? String
	raise "invalid output file name" unless output_file.is_a? String

	file = File.open(input_file, "r")
	data = file.read
	file.close
	data_lines = data.lines
	cleared_arr = []

	# path_strip(input_file, domain, output_file)
	# imports an xml file containing paths of the website's pages,
	# strips all unnecessary strings except for the path of the pages.
	## Parameters:
	# +input_file+ name of the input xml file
	# +domain+ the domain of the URL to exclude in the result
	# +output_file+ name of the output file, ending in .csv (preferred)
	def path_strip(input_file, domain, output_file)
	raise "domain must be string form" unless domain.is_a? String
	raise "invalid input file name" unless input_file.is_a? String

	DESIRED_SIZE = 1073741824 # 1gb
	FILE_NAME = "dummy" # name of the dummy file

	dummy_file = File.new(FILE_NAME, "w")

	while dummy_file.size < DESIRED_SIZE
	dummy_file.write([0,1].sample)
	end

	dummy_file.close

	def perfect_number? number
	return number == divisors_of(number)
	end

	def divisors_of number
	arr = []
	(1..number).each do \|iter\|
	if number % iter == 0
	arr << iter
	end

	require 'csv'

	# Data generation
	@data = {}

	(0..100).each do \|i\|
	@data[i] = {
	:age => Random.rand(18...80),
	:gender => Random.rand(0..1),
	:prescription_history => []

	require 'benchmark'

	the_number = 600_851_475_143

	# monkeypatching
	class Fixnum
	def prime? # O(n)
	(2..(self - 1)).each do \|divisor\|
	return false if self % divisor == 0
	end

	from decimal import *

	def compute_pi():
	pi = Decimal(3.0)
	curr_multiplier = Decimal(2)
	iteration = Decimal(0)
	load = Decimal(1)
	getcontext().prec = 6

	while 1: