# Stack
Stack is a data structure to store data in FILO (First-In Last-Out) format. For an example if you browse a website, browser will store your history and if you want to go back one page browser will know which page is your previous.


## How To Create It
### Create Your Stack Class
In this class it will have maximum data in the stack. If you dont want any limit data you can provide it '-1' value.

class Stack():
    # Constructor
    def __init__(self, data=None, size=-1):
        self.stack = []
        self.max_stack = -1

        if size is not None and size > 0:
            self.max_stack = size

        if data is not None:
            self.stack.append(data)

### Fullness Check Method
Implement our first method is checking if the stack is full by comparing `number of the data` to `maximum`.

def is_full(self):
    return len(self.stack) == self.max_stack

### Emptiness Check Method
Implement another checking method if the stack is empty by comparing `number of the data` to 0.

def is_empty(self):
    return len(self.stack) == 0

### Push Method
In the push method we will check if the stack is full or not before append new data into our stack. In this method we'll push new data into the top of the stack and return `None`.

def push(self, data):
    if not self.is_full():
        self.stack.append(data)

### Pop Method
In the pop method we will check if the stack is empty because we don't want to remove data from empty stack. In this method we'll get the top data and remove it from the stack.

def pop(self):
    if self.is_empty():
        return ""

    data = self.stack.pop()
    return data

### Peak Method
In the peak method is the same as pop but it does not remove data from stack.

def peek(self):
    if self.is_empty():
        return ""

    data = self.stack.pop()
    self.stack.append(data)
    return data

### Testing

def main():
    stack = Stack("https://www.google.com/")
    print("Search Wiki in Google")
    stack.push("https://www.google.com/search?q=wiki")
    print("Add 'https://www.google.com/search?q=wiki' into the stack")
    print("Click on the wiki link")
    stack.push("https://en.wikipedia.org/wiki/Wiki")
    print("Add 'https://en.wikipedia.org/wiki/Wiki' into the stack")
    print("Go back 1 page")
    print(f"Redirect from '{stack.pop()}' to '{stack.peek()}'")

if __name__ == "__main__":
    main()

## Resource
[GitHub](https://github.com/metaphorlism/data-structures/tree/main/stack)