python注释与代码风格

coding:utf-8

class Node(object):
“””生成双向链表的节点”””
def init(self, item):
self.item = item
self.next = None
self.prior = None

class DoubleLinkList(object):
“””双链表”””
def init(self, node=None):
self.__head = node # ****定义成私有的

def is_empty(self):
    """链表是否为空"""
    return self.__head is None

def length(self):
    """链表长度"""
    # cut游标，用来移动遍历结点
    cur = self.__head
    # count 记录数量
    count = 0   # 注意这个是0
    while cur is not None:  # 不用cur.next，用的话最后一个就直接跳出，不执行加1了
        count += 1
        cur = cur.next
    return count

def travel(self):
    """遍历整个链表"""
    cur = self.__head
    while cur is not None:
        print(cur.item, end=" ")
        cur = cur.next

def add(self, item):
    """链表表头添加，头插法"""

    node = Node(item)
    if self.is_empty():
        # 如果是空链表，将_head指向node
        self._head = node
    else:
        # 将node的next指向_head的头节点
        node.next = self._head
        # 将_head的头节点的prev指向node
        self._head.prior = node
        # 将_head 指向node
        self._head = node

def append(self, item):
    """尾插法"""
    node = Node(item)
    cur = self.__head   # 从头往后走，走到最后
    if self.__head is None:  # 判断是否为空
        self.__head = node
    else:
        while cur.next is not None:     # 用的是cur.next
            cur = cur.next      # 往后移动
        cur.next = node
        node.prior = cur

def insert(self, pos, item):
    """指定位置添加元素
    :param pos: 从0开始
    :param item:
    """
    if pos <= 0:
        self.add(item)
    elif pos > self.length():
        self.append(item)
    else:
        cur = self.__head     # 直接去找指的，不是__head
        count = 0
        while count < pos-1:    # 不是小于等于，寻找前一个节点
            cur = cur.next
            count += 1
        # 当循环退出后，prior指向pos位置
        node = Node(item)
        node.next = cur
        node.prior = cur.prior
        cur.prior.next = node
        cur.prev = node

def remove(self, item):
    """删除结点
    :param item:00
    """

    cur = self.__head
    while cur is not None:
        if cur.item == item:
            # 先判断是否是头结点
            if cur is self.__head:
                self.__head = cur.next
                if cur.next:
                    # 判断链表是否只有一个结点
                    cur.next.prior = None
            else:
                cur.prior.next = cur.next
                if cur.next:    # 达到最后
                    cur.next.prior = cur.prior
            # del cur
                print("删除%d成功" % item)
            break
        else:
            prior = cur
            cur = cur.next
    else:
        print("没有这个元素，删除失败")

def search(self, item):
    cur = self.__head
    count = 0
    if cur is None:
        return print("空的，查找%d失败" % item)
    else:
        while cur is not None:     # 是cur不是cur.next
            if cur.item == item:
                return count
            else:
                cur = cur.next
                count += 1
        print("查找%d失败,没有这个元素" % item)

if name == ‘main‘:
ll = DoubleLinkList()
print(ll.is_empty())

print(ll.length())
ll.add(0)
ll.append(1)
ll.append(2)
ll.append(5)
ll.append(3)
ll.add(20)
# 20 0 1 2 5 3
ll.insert(-1, 9)
ll.insert(3, 90)
# 9 20 0 90 1 2 5 3
ll.travel()
print("\n********************")
ll.search(3233)
ll.remove(5)
ll.travel()

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