Bitter Sweet Day

TREE AND HASH In this post, we will talk about TREE AND HASH in Data Structure. If you have learned about linked lists, queues, and stacks, we know that those data structures are called "linear" data structures because they all have a logical start and a logical end. However, tree and hash is not a "linear" data structure.  TREE A tree is a collection of nodes connected by directed (or undirected) edges. A tree stored its data in a hierarchy way. The easiest way to imagine it is by using a family tree. A tree can be empty with no nodes or a tree is a structure consisting of one node called the root and zero or one or more subtrees.  A tree has the following general properties: One node is distinguished as a root. Every node (exclude a root) is connected by a directed edge from exactly one other node; A direction is: parent -> children   Terminology summary Root...

LINKED LIST For the first meeting, I've learned about LINKED LIST. So what is linked list? Linked list is a dynamic data structure, where each element is a separate object. If in array we can easily access the elements in it by the index--because it stores the value in a consecutive memory location, in linked list we can’t do that because in linked list it uses random memory location. Now if you think “Then, isn't array better than?” well in array you can’t easily do insertions and deletions, but in linked list you can easily do push(for insertion) or pop(for deletion). Other than that, if in array you have to give a fixed memory to use in your program, in linked list the number of nodes is not fixed and can grow or shrink on demand, hence it’s called a dynamic data structure. This feature is very useful when you have to deal with an unknown number of objects. One of the disadvantage of linked list is that it uses more memory compares with an array, it adds an extra 4 b...

From my last post, I’ve talked about single linked list and double linked list, now we’re going to talk about STACK AND QUEUE. Both stack and queue is a linear data structure. Queues and stacks are also complementary in the actual use scenarios. So what is the difference between stack and queue?  In STACK the elements can be inserted and deleted only from one side of the list called the TOP and a stack follows the LIFO (Last In, First Out) principle, so the element inserted at the last is the first element to come out. In stack if you want to add a new node you can do push like in a single linked list and do pop if you want to remove a node. But remember that the added new node will be put on top or say at the end of the list and if you do pop or remove a node the one that will be removed will be the top or the recently added node. One of the applications for stack is an undo mechanism in a text editor. Here is a visualization of stack. For QUEUE the elements ca...