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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.

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# recursion
def fib(n):
    if n <= 1:
        return n

    return fib(n-1) + fib(n-2)

# recursion with memoization
def fib_memo(n, lookup=None):
    """

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Array.from(document.getElementsByClassName('outdated-comment')).forEach(l => l.classList.add('open'));

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TIL how to make deprecation warnings:

Compiling 2 files (.ex)
warning: `Retort.Resources.timeout/2` is deprecated; call `Retort.Resources.Timeout.get_or_default/2` instead.
  lib/retort/resources.ex:197: Retort.Resources.timeout/2

Function to be replaced

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defmodule Map.Helpers do
  @moduledoc """
  Functions to transform maps
  """

  @doc """
  Convert map string camelCase keys to underscore_keys
  """
  def underscore_keys(nil), do: nil

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# decode_session_cookie.rb
# ------------------------
# The purpose of this script is to show that if I have the secret_key_base
# and a cookie to an active Rails session, I can decrypt it and gain access
# to key information about the user's session.

require 'rubygems'
require 'cgi'
require 'active_support'
require 'action_controller'

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Generate a new Elixir project using mix and add cowboy and plug as dependencies in mix.exs:

  defp deps do
    [
      {:cowboy, "~> 1.0.0"},
      {:plug, "~> 0.8.1"}
    ]
  end

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>Ansi 0 Color</key>
	<dict>
		<key>Alpha Component</key>
		<real>1</real>
		<key>Blue Component</key>
		<real>0.11759774386882782</real>

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defmodule Expng do

  defstruct [:width, :height, :bit_depth, :color_type, :compression, :filter, :interlace, :chunks]

  def png_parse(<<
  0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A,
                 _length :: size(32),
                 "IHDR",
                 width :: size(32),
                 height :: size(32),

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# foo/lib/foo/accounts/accounts.ex

defmodule Foo.Accounts do
  @moduledoc """
  The boundary for the Accounts system.
  """

  import Ecto.{Query, Changeset}, warn: false
  alias Foo.Repo