DataStructures

This Repository will have programs to understand Data structures in java with notes.

1. Stack: Stack is a LIFO Data structure

   • Store objects in to a sort of "vertical tower"
   • push and pop are methods to insert and remove elements.
   • Uses of stack:
     1. undo/redo features in text editor
     2. moving back/forward through browser history
     3. backtracking algo's (maze, file directories)
     4. calling functions

2. Queue: FIFO data structure eg. line of people

   • linear data structure
   • add/offer and remove/poll are two method of adding and removing elements.
   • adding elements is called enqueuing and removing is called dequeue'ing.
   • Queue is an interface and cannot be instantiated so create a LinkedList
   • Uses of queue:
     1. Keyboard buffer(letters should appear on the screen in order they are passed )
     2. Printer Queue
     3. Used in LinkedList, PriorityQueues, BFS.

3. Priority Queues:

   FIFO data structure that serves elements with the highest priorities first before elements with lower priority.

4. LinkedList: LinkedList vs Array/ArrayList:

   Array/ArrayList:

   • store elements in continuous memory location.
   • fantastic when accessing elements randomly but not efficient at inserting and deleting the elements

   LinkedList: (singly)

   • long chain of nodes where node structure has data and next as its properties
   • non-continuous
   • no shifting of elements is required at the time of insertion and deletion.
   • searching elements takes time in LinkedList.
   • doubly LinkedList take more memory and can traverse both ways back and forth.
   • LinkedList can be used as stack by using push() and pop().