python注释与代码风格

难

# coding: utf-8


class Node(object):
    """单向循环链表的节点"""
    def __init__(self, elem):
        self.elem = elem
        self.next = None


class SingleCycleLinkList(object):
    """单向循环链表"""
    def __init__(self, node=None):
        self.__head = node   # ****定义成私有的
        if node:
            node.next = node

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

    def length(self):
        """链表长度"""
        if self.is_empty():
            return 0
        # cut游标，用来移动遍历结点
        cur = self.__head
        # count 记录数量
        count = 1   # 注意这个是1了
        while cur.next != self.__head:  # 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.next != self.__head:
            print(cur.elem, end=" ")
            cur = cur.next
        # 退出循环，cur执行为节点，但为节点的元素未打印
        print(cur.elem)

    def add(self, item):
        """链表表头添加，头插法"""
        node = Node(item)
        if self.is_empty():
            self.__head = node
            node.next = node
        else:
            cur = self.__head
            while cur.next != self.__head:
                cur = cur.next
            # 退出循环，cur指向尾结点
            node.next = self.__head
            cur.next = 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 != self.__head:     # 用的是cur.next
                cur = cur.next      # 往后移动
            node.next = self.__head
            cur.next = node

    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()-1:
            self.append(item)
        else:
            prior = 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
                prior = prior.next
                count += 1
            # 当循环退出后，prior指向pos - 1位置
            node = Node(item)
            node.next = prior.next
            prior.next = node

    def remove(self, item):
        """删除结点
        :param item:00
        """
        if self.is_empty():
            return False
        prior = None
        cur = self.__head
        while cur.next != self.__head:
            if cur.elem == item:
                # 先判断是否是头结点
                if cur == self.__head:
                    # 头结点的情况
                    # 找尾结点
                    rear = self.__head
                    while rear.next != self.__head:
                        rear = rear.next
                    self.__head = cur.next
                    rear.next = self.__head
                else:
                    # 中间节点
                    prior.next = cur.next
                    print("删除%d成功" % item)
                return
            else:
                prior = cur
                cur = cur.next
        if cur.elem == item:
            if cur == self.__head:
                self.__head is None
            else:
                prior.next = cur.next

        else:
            print("没有这个元素，删除失败")

    def search(self, item):
        count = 0
        if self.is_empty():
            return print("空的，查找%d失败" % item)
        else:
            cur = self.__head
            while cur.next != self.__head:     # 是cur不是cur.next
                if cur.elem == item:
                    return count
                else:
                    cur = cur.next
                    count += 1
            if cur.elem == item:
                return True
            print("查找%d失败,没有这个元素" % item)


if __name__ == '__main__':
    ll = SingleCycleLinkList()
    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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