We need to understand stack because it uses the principle "last in, first out." rather than arrays that just replicate the concepts that I will be using today.
What is the difference between arrays and data encryption?
Similar to a collection of boxes, arrays can hold various items. Each box can contain letters, numbers, or other objects. Another option is to combine several boxes to create one large box. This is helpful when you need to keep a lot of data in one location.
Stacks and arrays are two distinct data structures with different uses. A stack can, however, be implemented using an array. In this approach, the stack's elements are stored in an array, and a top pointer tracks the top element of the stack. When an element is added to the stack, the value of top is increased, and the element is added to the newly created top slot. When we remove an element from a stack, we decrease the top value and delete the element at the top of the stack.
Data Encryption and Caesar
Data encryption is similar to locking your secret message in a safe that can only be opened by you and the recipient. The safe features a unique lock that can only be unlocked with a unique key. This will prevent anyone else who receives the message from reading it since they need the necessary key to access the safe.
For example, it is a straightforward method for encrypting and decrypting text using the Caesar cipher, which includes moving alphabetic characters to a predetermined number of locations. It gives users a fundamental understanding of data encryption using a traditional cipher mechanism by allowing them to interactively input plaintext, encrypt it, and optionally decrypt it. It's a simple encryption technique that involves shifting the letters of a message a certain number of places down the alphabet. For example, if we were to use a Caesar cipher with a shift of 3, the letter "A" would become "D", "B" would become "E", and so on.
The teachings I will discuss today are Stack, Push, Pop, Overflow Condition, Underflow Condition, and Top Variable.
A stack is a linear data structure that stores data items and follows the principle of "Last in, First Out" (LIFO). It is an ordered list that adds new data items and deletes already known data items from one end known or top of the stack. Insertion/addition and deletion operation is known as Push or Pop operations.
Push: It is a process of inserting or adding an element in the stack. It is called a push operation.
Pop: The process of removing an element from the stack is called pop operation.
Overflow Condition: An overflow condition occurs when the stack is full, and the user can not add a new item.
Underflow Condition: When the stack is empty, and there is no item in the stack, then underflow condition has occurred.
Top Variable: The top is a particular variable type that can identify the overflow or underflow stack. We can initialize the leading variable with -1.
Examples of Java Methods using stack:
Push (e) into the stack such that it is at the top.
pop(): Removes an element from the stack and returns the top element; if the stack is empty, an error is raised.
size(), which returns the number of elements in the stack. isEmpty(): Indicate whether the stack is empty by returning a Boolean value.
top() returns the top element in a stack without deleting it; an error is raised if the stack is empty.
This is a brief video that uses stacks in Java language in a simplier way:
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