数据结构 队列（带尾节点的单链表实现） 回顾练习

带尾节点的单链表队列 入队0（1） 出队0（1）

#!/usr/bin/env python3

class QueueUnderflow(ValueError):
        pass

class Node(object):
        def __init__(self, elem, next_=None):
                self.elem = elem
                self.next = next_

#queue_list
class LQueue(object):
        def __init__(self):
                self.head = None
                self.rear = None
                self.num = 0

        def is_empty(self):
                return self.head is None

        def count(self):
                return self.num

        def dequeue(self):
                p = self.head
                if not p:
                        raise QueueUnderflow
                e = p.elem
                self.head = p.next
                self.num -= 1
                return e

        def enqueue(self, elem):
                p = self.head
                if not p:
                        self.head = Node(elem, self.head)
                        self.rear = self.head
                        self.num += 1
                        return
                self.rear.next = Node(elem)
                self.rear = self.rear.next
                self.num += 1

        def peek(self):
                p = self.head
                if not p:
                        raise QueueUnderflow
                e = p.elem
                return e

        def bianli(self):
                p = self.head
                li = []
                while p:
                        li.append(p.elem)
                        p = p.next
                return li

if __name__ == '__main__':
        lq = LQueue()
        l = [1,2,3,4,5]
        for i in l:
                lq.enqueue(i)
        print(lq.bianli())
        lq.dequeue()
        print(lq.peek())