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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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#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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#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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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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#The Quick Sort is a popular sorting algorithm, which has been discussed in detail, with examples and C code over here : Arrays and Sorting: Quick Sort ( with C Program source code). In this tutorial, we will take a quick look at the ruby implementation of Quick Sort.

#1

def partition arr, lo, hi  
  i,j = lo+1,hi
  while true

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#Selection Sort


#The Selection Sort is a popular quadratic sorting algorithm, which has been discussed in detail, with examples and C code over here : Arrays and Sorting: Selection Sort ( with C Program source code). In this tutorial, we will take a quick look at the ruby implementation of Selection Sort.

# Selection Sort *************************
# Selection Sort -> A popular quadratic sorting algorithm with O(n^2) complexity
# For Index [i] -> swap the i-th smallest element from (array[i]....array[length-1]) with array[i-1]  
def selectionSort(arr)
    for index in 0..(arr.length-1)

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#Algorithm and Data Structures
# More details: http://www.theodinproject.com/ruby-programming/common-data-structures-and-algorithms

# Implementation of Insertion Sort.

# Insertion Sort ************************
# Insertion Sort -> A popular quadratic sorting algorithm with O(n^2) complexity
def insertionSort(arr)
    for size in 2..arr.length
        # Remember, this is a zero-start array

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 An API is an “application program interface”, which basically means a computer program that allows other programs to
 communicate with it. In our case, our program will be a web application, and we want to make it easy for other web apps
 to connect to it.
 
 Example: let’s say I want to build a simple web app that searches Twitter for tweets that contain certain keywords.
 I can use Twitter’s search API to do just that by sending a request for data to their servers and then manipulating or
 displaying that data on my app. There are tons of APIs out there that make their data available to developers for things
 like movie times, restaurant reviews, social media, any pretty much everything else.
 

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##

* ORM is Object Relational Mapper. It means you don't have to manually call the database yourself; the ORM handles it for you.
* Ruby on Rails uses one called ActiveRecord, and it's a really good one.
* ORM allows you to do things such as:
      User.find(50).contacts
      Instead of manually writing a SELECT statement with JOINs, WHEREs, etc.
      
**********

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Problem: Every push prompt me to input username and password.
I would like to avoid it for every push, but how to configure to avoid it?

Answer: Using SSH authentication on terminal.

1. Generate an SSH key

Linux/Mac
Open terminal to create ssh keys: