LinkedList- (2) DoublyLinkedList with python

연결리스트

단일 연결리스트는 앞서 (1) SingleLinkedList 에서 다뤄봤고 이번에는 전방 탐색도 가능한 DoublyLinkedList 이중연결리스트를 정리했다.

이중 연결리스트 자세한 설명

(2) DoublyLinkedList

from typing import Any, Type

class Node:
    def __init__(self, data: Any, prev = None, next = None) -> None:
        self.data = data
        self.prev = prev
        self.next = next


class DoublyLinkedList:
    def __init__(self) -> None:
        self.no = 0
        self.head = self.tail = None
        self.cur = None

    def __len__(self):
        return self.no

    def add_first(self, data: Any):
        self.no += 1
        if self.head is not None:
            ptr = self.head
            self.head = self.cur = Node(data)
            self.head.next = ptr
            ptr.prev = self.head
        else:
            self.head = Node(data)
            self.tail = self.head

    def add_last(self, data: Any):
        self.no += 1
        if self.tail is not None:
            ptr = self.tail
            self.tail = self.cur = Node(data)
            self.tail.prev = ptr
            ptr.next = self.tail
        else:
            self.tail = Node(data)
            self.head = self.tail

    def remove_first(self):
        if self.head is None:
            return False
        else:
            self.head = self.cur = self.head.next
            self.head.prev = None
            self.no -= 1
            return True

    def remove_last(self):
        if self.tail is None:
            return False
        else:
            self.tail = self.cur = self.tail.prev
            self.tail.next = None
            self.no -= 1
            return True

    def print(self):
        ptr = self.head
        while ptr is not None:
            print(f'{ptr.data} ->')
            ptr = ptr.next

    def reverse_print(self):
        ptr = self.tail
        while ptr is not None:
            print(f'{ptr.data} ->')
            ptr = ptr.prev



dlst = DoublyLinkedList()
dlst.add_first(2)
dlst.add_first(3)
dlst.add_first(4)
dlst.add_first(5)
dlst.add_last(6)
dlst.add_last(7)
dlst.add_last(8)
dlst.add_last(9)

dlst.remove_first()
dlst.remove_last()
dlst.reverse_print()
print()
dlst.print()
print()
print(len(dlst))

8 ->
7 ->
6 ->
2 ->
3 ->
4 ->

4 ->
3 ->
2 ->
6 ->
7 ->
8 ->

6