【数据结构】单向循环链表

class Node(object):
    """节点"""
    def __init__(self, item):
        self.item = item
        self.next = None
class SinCycLinkedlist(object):
    """单向循环链表"""
    def __init__(self):
        self._head = None
    def is_empty(self):
        """判断链表是否为空"""
        return self._head == None
    def length(self):
        """返回链表的长度"""
        # 如果链表为空，返回长度0
        if self.is_empty():
            return 0
        count = 1#此处区别于单链表，单链表此处count=0
        cur = self._head
        while cur.next != self._head:#尾部等于头部
            count += 1
            cur = cur.next
        return count
    def travel(self):
        """遍历链表"""
        if self.is_empty():
            return
        cur = self._head
        print cur.item,
        while cur.next != self._head:
            cur = cur.next
            print cur.item,
        print ""
    def add(self, item):
        """头部添加节点"""
        node = Node(item)#需要加具体值元素的时候，开始实例化节点，然后加入链表结构
        if self.is_empty():
            self._head = node
            node.next = self._head
        else:
            #添加的节点指向_head
            node.next = self._head
            # 移到链表尾部，将尾部节点的next指向node
            cur = self._head
            while cur.next != self._head:
                cur = cur.next
            cur.next = node
            #_head指向添加node的
            self._head = node
    def append(self, item):
        """尾部添加节点"""
        node = Node(item)
        if self.is_empty():
            self._head = node
            node.next = self._head
        else:
            # 移到链表尾部
            cur = self._head
            while cur.next != self._head:
                cur = cur.next
            # 将尾节点指向node
            cur.next = node
            # 将node指向头节点_head
            node.next = self._head
    def insert(self, pos, item):
        """在指定位置添加节点"""
        if pos  (self.length()-1):
            self.append(item)
        else:
            node = Node(item)
            cur = self._head
            count = 0
            # 移动到指定位置的前一个位置
            while count 
[1]: https://xuan.ddwoo.top/index.php/archives/155/
[2]: https://xuan.ddwoo.top/index.php/archives/154/