Lekcja 15

class Stack:
    def __init__(self):
        self.stack = []

    def push(self, item):
        self.stack.append(item)

    def pop(self):
        if not self.is_empty():
            return self.stack.pop()

    def peek(self):
        if not self.is_empty():
            return self.stack[-1]

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

    def size(self):
        return len(self.stack)

stack = Stack()

stack.push(1)
stack.push(2)
stack.push(3)

print(stack.pop())  # 3
print(stack.peek())  # 2
print(stack.is_empty())  # False
print(stack.size())  # 2




class Queue:
    def __init__(self):
        self.queue = []

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

    def enqueue(self, item):
        self.queue.append(item)

    def dequeue(self):
        if self.is_empty():
            return None
        else:
            return self.queue.pop(0)

queue = Queue()

queue.enqueue(1)
queue.enqueue(2)
queue.enqueue(3)

print(queue.dequeue())  # 1
print(queue.dequeue())  # 2
print(queue.is_empty())  # False
print(queue.dequeue())  # 3
print(queue.is_empty())  # True





class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

class LinkedList:
    def __init__(self):
        self.head = None

    def append(self, data):
        new_node = Node(data)
        if self.head is None:
            self.head = new_node
            return
        last_node = self.head
        while last_node.next is not None:
            last_node = last_node.next
        last_node.next = new_node

    def display(self):
        if self.head is None:
            print("Lista jest pusta")
            return
        current_node = self.head
        while current_node is not None:
            print(current_node.data, end=" -> ")
            current_node = current_node.next
        print("None")

my_list = LinkedList()
my_list.append(1)
my_list.append(2)
my_list.append(3)
my_list.display()



def is_palindrome(string):
    stack = Stack()
    for char in string:
        stack.push(char)
    reversed_string = ""
    while not stack.is_empty():
        reversed_string += stack.pop()
    return string == reversed_string