python实现简单单向循环链表

# -*- coding: utf-8 -*-


class Node(object):
    """节点"""
    def __init__(self, data):
        self.data = data
        self.next = None


class SingleCycleLinkList(object):
    """单向循环链表"""
    def __init__(self, node=None):
        self.__head = node
        if node:
            node.next = node

    @property
    def is_empty(self):
        return self.__head is None

    @property
    def length(self):
        """链表长度"""
        # cur游标，用来移动遍历节点
        cur = self.__head
        # count记录数量
        count = 0
        while cur:
            if cur.next is self.__head:
                return count + 1
            count += 1
            cur = cur.next
        return count

    @property
    def travel(self):
        """遍历整个链表"""
        # cur游标，用来移动遍历节点
        cur = self.__head
        while cur:
            if cur.next == self.__head:
                print(cur.data)
                return
            print(cur.data, end=' ')
            cur = cur.next

    def add(self, elem):
        """链表头部添加元素,头插法"""
        node = Node(elem)
        if self.is_empty:
            self.__head = node
            node.next = node
            return
        node.next = self.__head
        cur = self.__head
        while cur:
            if cur.next == node.next:
                self.__head = node
                cur.next = node.next
                cur.next = node
                return
            cur = cur.next

    def append(self, elem):
        """链表尾部添加元素,尾插法"""
        node = Node(elem)
        if self.is_empty:
            self.__head = node
            node.next = node
        else:
            cur = self.__head
            while cur.next != self.__head:
                cur = cur.next
            node.next = cur.next
            cur.next = node

    def insert(self, pos, elem):
        """指定位置添加元素"""
        if pos == 0:
            self.add(elem)
        elif pos > (self.length-1):
            self.append(elem)
        elif pos < 0:
            if abs(pos) > self.length:
                self.add(elem)
            else:
                node = Node(elem)
                count = 0
                cur = self.__head
                while cur:
                    if (count+abs(pos)) == self.length:
                        node.next = cur.next
                        cur.next = node
                        break
                    cur = cur.next
                    count += 1
        else:
            node = Node(elem)
            count = 0
            cur = self.__head
            while (count+1) < pos:
                cur = cur.next
                count += 1
            node.next = cur.next
            cur.next = node

    def remove(self, elem):
        """删除节点"""
        if self.is_empty:
            return
        cur = self.__head
        count = 0
        # 头节点处理
        if cur.data == elem:
            pos = self.__head
            while pos.next != self.__head:
                pos = pos.next
            self.__head = cur.next
            pos.next = self.__head
            return count, elem
        while cur.next:
            # 尾节点处理
            if cur.next == self.__head:
                if cur.next.data == elem:
                    cur.next = cur.next.next
                    return count + 1, elem
                return
            # 其他节点处理
            else:
                if cur.next.data == elem:
                    cur.next = cur.next.next
                    return count+1, elem
                cur = cur.next
                count += 1

    def is_contain(self, elem):
        """查找节点是否存在"""
        cur = self.__head
        while cur:
            if cur.next == self.__head:
                if cur.data == elem:
                    return True
                return False
            else:
                if cur.data == elem:
                    return True
                cur = cur.next
        return False

    def search(self, elem):
        """查找节点所在位置"""
        cur = self.__head
        count = 0
        while cur:
            if cur.next == self.__head:
                if cur.data == elem:
                    return count
                return
            else:
                if cur.data == elem:
                    return count
                cur = cur.next
                count += 1
        return


if __name__ == '__main__':
    ll = SingleCycleLinkList()
    print(ll.is_empty)
    print(ll.length)

    print(ll.remove(1))
    ll.add(0)
    ll.append(1)
    print(ll.is_empty)
    print(ll.length)
    ll.travel

    ll.append(2)
    ll.append(3)
    ll.append(4)
    ll.append(5)
    ll.travel
    ll.add(8)
    ll.add(9)
    ll.add(10)
    ll.travel
    print(ll.search(8))
    print(ll.search(3))
    print(ll.search(6))
    print(ll.search(5))
    print(ll.is_contain(8))
    print(ll.is_contain(3))
    print(ll.is_contain(6))
    print(ll.is_contain(5))
    ll.travel
    print(ll.remove(8))
    ll.travel
    print(ll.remove(10))
    ll.travel
    print(ll.remove(5))
    ll.travel
    print(ll.remove(6))
    ll.travel
    ll.insert(-3, 0)
    ll.travel
    ll.insert(-9, 89)
    ll.travel