數(shù)據(jù)結(jié)構(gòu)鏈表之隊(duì)列

隊(duì)列概述

• 定義：隊(duì)列是一種基于先進(jìn)先出(FIFO)的數(shù)據(jù)結(jié)構(gòu)，隊(duì)列只能在一段進(jìn)行插入和刪除操作的結(jié)構(gòu)，第一個(gè)進(jìn)入隊(duì)列的元素在讀取時(shí)會(huì)第一個(gè)被讀取

隊(duì)列可以使用順序表(Python中列表)實(shí)現(xiàn)，也可以用鏈表實(shí)現(xiàn)，這里介紹鏈表實(shí)現(xiàn)的方法

主要實(shí)現(xiàn)以下幾個(gè)功能：

is_empty()判斷是否隊(duì)列為空

size()查看隊(duì)列長(zhǎng)度

enqueue()向隊(duì)列插入元素

dequeue()從隊(duì)列的頭部取出一個(gè)元素

重寫(xiě)__iter__()和__next__()實(shí)現(xiàn)遍歷功能

Python代碼實(shí)現(xiàn)

class Node:def __init__(self, item):"""Define linked list node"""self.item = itemself.next = Noneclass Queue:def __init__(self):self.head = Noneself.last = Noneself.len = 0def is_empty(self):return self.len == 0def size(self):return self.lendef enqueue(self, item):"""Enqueue an element into this queue"""node = Node(item)if not self.last:self.head = nodeelse:self.last.next = nodeself.last = nodeself.len += 1def dequeue(self):"""Dequeue an element from this queue"""if self.head != self.last:# Has at least two elementsres = self.headself.head = self.head.nextself.len -= 1return res# Has one or zero elementres = self.headself.head = Noneself.last = Noneself.len -= 1return resdef __iter__(self):self.cur = self.headreturn selfdef __next__(self):try:temp = self.curself.cur = self.cur.nextreturn tempexcept AttributeError as e:raise StopIteration

功能驗(yàn)證

if __name__ == '__main__':queue = Queue()print(f"Is empty? {queue.is_empty()}")queue.enqueue(1)queue.enqueue(2)queue.enqueue(3)queue.enqueue(4)print(f"Show all elements in this queue: {[i.item for i in queue]}")print(f"Length of this queue: {queue.len}")print(f"Dequeue an element, its value: {queue.dequeue().item}")print(f"After dequeuing an element, length of this queue: {queue.len}")

打印結(jié)果:

Is empty? True Show all elements in this queue: [1, 2, 3, 4] Length of this queue: 4 Dequeue an element, its value: 1 After dequeuing an element, the length of this queue: 3

總結(jié)

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