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def mergeArrays(arr,start_1,end_1,start_2,end_2)

    temp = Array.new(end_1 + end_2 - start_1 - start_2 + 2)
    index_1 = start_1  # Marks the index in the first sub-array, which needs to be put into the temporary array next
    index_2 = start_2  # Marks the index in the second sub-array, which needs to be put into the temporary array next
    index = 0        # Mark the index in the Temporary array which is being filled
     

    while ( index_1 <= end_1 ) || ( index_2 <= end_2 )
        

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#Ruby doesn't provide an explicit 'stack' but for all practical purposes, the Array provided by Ruby can be treated as a full-fledged stack.

# Based on the ideas from : http://macdevelopertips.com/ruby/using-a-stack-with-ruby.html
# Stacks are a Last In First Out Data Structure

class Stack
    def initialize
        @elements = []
    end
    

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#Queues as provided by Ruby.


require 'thread'

# Queues are a First in First Out Data Structure
# Ruby provides you with synchronoized/thread-safe queues 

testQueue = Queue.new
testQueue.enq(10)

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# Quick Example of a Self Referential Data Structure in Ruby 
# NODE -> contains a value and a pointer to (next_node)
# LinkedList -> This class holds the linked list functions - adding a node, traversing and displaying the linked list

class Node

    attr_accessor :value, :next_node

    def initialize val,next_in_line
        @value = val

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# Example of Self-Referential Data Structures - A Binary Tree

class TreeNode
    attr_accessor :value, :left, :right
    
    # The Tree node contains a value, and a pointer to two children - left and right 
    # Values lesser than this node will be inserted on its left
    # Values greater than it will be inserted on its right
    def initialize val,left,right
        @value = val

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## More details: http://ruby.bastardsbook.com/chapters/recursion/

#1
def countdown(n)
  return if n.zero? # base case
  puts n
  countdown(n-1)    # getting closer to base case 
end               

countdown(5) # > 5 4 3 2 1

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TO LEARN: https://curl.haxx.se/docs/httpscripting.html

Why cURL?
Because: http://code.tutsplus.com/tutorials/techniques-for-mastering-curl--net-8470

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HTML: 
<div class="hover_img">
    <a href="http://ddeveloperr.github.io/p1/" target="_blank">Build a Simple Google Clone Website<span><img src="img/1_google_clone.jpg" alt="image" height="100" /></span></a>
</div>
    				

CSS:
.hover_img a { position:relative; }
.hover_img a span { position:absolute; display:none; z-index:99; }

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Migration Overview
Migrations are a convenient way to alter your database schema over time in a consistent and easy way.
They use a Ruby DSL so that you don't have to write SQL by hand, allowing your schema and changes to be 
database independent.

db:migrate runs (single) migrations that have not run yet.
db:create creates the database
db:drop deletes the database
db:schema:load creates tables and columns within the (existing) database following schema.rb

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Deep learning here: https://www.youtube.com/watch?v=y57OnWV6dRE
                    https://gorails.com/episodes/the-params-hash?autoplay=1