====== Data Structures ======

===== Big O =====
  * Finding all subsets of a set ''O(2^n)''
  * Finding all permutations of a string ''O(n!)''
  * Binary search ''O(log n)''
  * Sorting using mergesort ''O(n log(n))''
  * Iterating over all cells of a matrix (m,n) ''O(m*n)''

==== Linked Lists ====
Singly Linked List time complexities
  * Search ''O(n)''
  * Insert at head ''O(1)''
  * Inset at tail ''O(1)''
  * Remove at head ''O(1)''
  * Remove at tail ''O(n)''
  * Remove in middle ''O(n)''

Doubly Linked List time complexities
  * Search ''O(n)''
  * Insert at head ''O(1)''
  * Inset at tail ''O(1)''
  * Remove at head ''O(1)''
  * Remove at tail ''O(1)''
  * Remove in middle ''O(n)''

==== Stack ====
Usage examples  
  * Undo mechanisms in text editors
  * Compiler syntax checking for matching brackets and braces
  * Can model pile of objects
  * Used behind the scenes to support recursion by keeping track of previous function calls
  * Depth First Search (DFS) on a graph

Time complexity analysis (implemented using LinkedList)
  * Pushing ''O(1)''
  * Popping ''O(1)''
  * Peeking ''O(1)''
  * Searching ''O(n)''
  * Size ''O(1)''

==== Queues ====
A queue is a linear data structure which models real world queues by having two primary operations ''enqueue'' and ''dequeue''.

Usage
  * Any waiting line models (lineup at a movie theater, McDonald waiting numbers)
  * Can be used to keep track of the ''n'' most recently added elements
  * Web server request management where you want first come first serve
  * Breadth first search (BFS) graph traversal

Time complexity analysis
  * Enqueue ''O(1)''
  * Dequeue ''O(1)''
  * Peeking ''O(1)''
  * Contains ''O(n)''
  * Removal ''O(n)''
  * Is Empty ''O(1)''