KevinSia

## next_academy_solution_Database_Drill:_SQL_Tutor.md

      
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                KevinSia
                / next_academy_solution_Database_Drill:_SQL_Tutor.md
            
            
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              April 9, 2016 18:16
            
          
    #SQL notes

SELECT within SELECT

select each country in Europe and show their population in percentage of population of Germany

SELECT name, CONCAT(ROUND(population/(SELECT population FROM world WHERE NAME = 'Germany')*100), '%') 
FROM world
WHERE continent = 'Europe'

ALL to run through a database list made with SELECT


## elegant_sudoku_solver.rb
require 'Benchmark'

class Sudoku
  attr_accessor :puzzle

  def initialize
    @puzzle = ''
    @game = Array.new(9)
    @game.map! { Array.new(9) }
    9.times do |i|

## index.html
<!DOCTYPE html>
<html>
<head>
<script src="https://fb.me/react-15.1.0.js"></script>
<script src="https://fb.me/react-dom-15.1.0.js"></script>
  <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" rel="stylesheet" type="text/css" />
  <meta charset="utf-8">
  <title>JS Bin</title>
</head>
<body>

## basics.md

      
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                KevinSia
                / basics.md
            
            
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              April 18, 2017 19:01
            
          
    SAPPHIRE EMERALD DIAMOND PEARL

RUBY!


Fun fact

https://en.wikipedia.org/wiki/History_of_programming_languages


Script

A script is a text file containing commands/codes/instructions that you write and pass to the a program to run.


Terminal

Also known as shell


The shell is a program that takes keyboard commands and passes them to the operating system to carry out.


## display_triangles.rb
def triangle_up(num, char)
  1.upto(num) { |i| puts char * i }
end

def triangle_down(num, char)
  num.downto(1) { |i| puts char * i }
end

## deaf_aunty.rb
def deaf_aunty
    conversation_done = false

    until conversation_done
      puts 'Say something to aunty'
      reply = gets.chomp

      if reply == reply.upcase
        puts 'NO, WE CAN\'T DO THAT!'
      elsif reply == 'I love ya, aunty, but I\'ve got to go'

## roman_numerals.rb
def to_roman(num)
  str = ''
  # Your code here
  if num >= 1000
    str += 'M' * (num / 1000)
    num %= 1000
  end

  if num == 900
    str += 'CM'

## anagrams_1.rb
def canonical(word)
  word.downcase.chars.sort
end

def is_anagram?(word1, word2)
  canonical(word1) == canonical(word2)
end

puts "One word"
word1 = gets.chomp

## dictionary_sort.rb
# Your code here to sort the array
def dictionary_sort(array)
  return if array.length <= 1
  array.sort { |word1, word2| word1.downcase <=> word2.downcase }
end

# writing `array.sort` is equivalent to writing `array.sort { |i, j| i <=> j }`
# .sort decides which item should be in the front by doing `<=> on each pair of items
# if the block gives -1, i goes to the front and j goes to the back
# if the block gives 1, j goes to the front and i goes to the back

## shuffle.rb
# Fisher-Yates shuffle
# the wiki shows two examples
# https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle

# pencil-and-paper method
# 1. Duplicate the array and shuffle the duplicate instead (we call the duplicate `input_array`)
# 2. Generate a random number between 0 and (length of the array - 1) (we call the number `random_position`)
# 3. Take an element at position `random_position` in the `input_array`, and put into another array
# 4. Repeat 2-3 until `input_array` has nothing left
	require 'Benchmark'

	class Sudoku
	attr_accessor :puzzle

	def initialize
	@puzzle = ''
	@game = Array.new(9)
	@game.map! { Array.new(9) }
	9.times do \|i\|
	<!DOCTYPE html>
	<html>
	<head>
	<script src="https://fb.me/react-15.1.0.js"></script>
	<script src="https://fb.me/react-dom-15.1.0.js"></script>
	<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" rel="stylesheet" type="text/css" />
	<meta charset="utf-8">
	<title>JS Bin</title>
	</head>
	<body>
	def triangle_up(num, char)
	1.upto(num) { \|i\| puts char * i }
	end

	def triangle_down(num, char)
	num.downto(1) { \|i\| puts char * i }
	end
	def deaf_aunty
	conversation_done = false

	until conversation_done
	puts 'Say something to aunty'
	reply = gets.chomp

	if reply == reply.upcase
	puts 'NO, WE CAN\'T DO THAT!'
	elsif reply == 'I love ya, aunty, but I\'ve got to go'
	def to_roman(num)
	str = ''
	# Your code here
	if num >= 1000
	str += 'M' * (num / 1000)
	num %= 1000
	end

	if num == 900
	str += 'CM'
	def canonical(word)
	word.downcase.chars.sort
	end

	def is_anagram?(word1, word2)
	canonical(word1) == canonical(word2)
	end

	puts "One word"
	word1 = gets.chomp
	# Your code here to sort the array
	def dictionary_sort(array)
	return if array.length <= 1
	array.sort { \|word1, word2\| word1.downcase <=> word2.downcase }
	end

	# writing `array.sort` is equivalent to writing `array.sort { \|i, j\| i <=> j }`
	# .sort decides which item should be in the front by doing `<=> on each pair of items
	# if the block gives -1, i goes to the front and j goes to the back
	# if the block gives 1, j goes to the front and i goes to the back
	# Fisher-Yates shuffle
	# the wiki shows two examples
	# https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle

	# pencil-and-paper method
	# 1. Duplicate the array and shuffle the duplicate instead (we call the duplicate `input_array`)
	# 2. Generate a random number between 0 and (length of the array - 1) (we call the number `random_position`)
	# 3. Take an element at position `random_position` in the `input_array`, and put into another array
	# 4. Repeat 2-3 until `input_array` has nothing left