本文實例講述了python單向循環鏈表原理與實現方法。分享給大家供大家參考，具體如下：

單向循環鏈表

單鏈表的一個變形是單向循環鏈表，鏈表中最后一個節點的next域不再為None，而是指向鏈表的頭節點。

操作

實現

# -*- coding:utf-8 -*-#! python3class Node(object):  """節點"""  def __init__(self, item):    self.item = item    self.next = Noneclass SinCycLinkedlist(object):  """單向循環鏈表"""  def __init__(self):    self.__head = None  def is_empty(self):    """判斷鏈表是否為空"""    return self.__head == None  def length(self):    """返回鏈表的長度"""    # 如果鏈表為空，返回長度0    if self.is_empty():      return 0    count = 1    cur = self.__head    while cur.next != self.__head:      count += 1      cur = cur.next    return count  def travel(self):    """遍歷鏈表"""    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):    """頭部添加節點"""    node = Node(item)    if self.is_empty():      self.__head = node      node.next = self.__head    else:      # 添加的節點指向_head      node.next = self.__head      # 移到鏈表尾部，將尾部節點的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):    """尾部添加節點"""    node = Node(item)    if self.is_empty():      self.__head = node      node.next = self.__head    else:      # 移到鏈表尾部      cur = self.__head      while cur.next != self.__head:        cur = cur.next      # 將尾節點指向node      cur.next = node      # 將node指向頭節點_head      node.next = self.__head  def insert(self, pos, item):    """在指定位置添加節點"""    if pos <= 0:      self.add(item)    elif pos > (self.length() - 1):      self.append(item)    else:      node = Node(item)      cur = self.__head      count = 0      # 移動到指定位置的前一個位置      while count < (pos - 1):        count += 1        cur = cur.next      node.next = cur.next      cur.next = node  def remove(self, item):    """刪除一個節點"""    # 若鏈表為空，則直接返回    if self.is_empty():      return    # 將cur指向頭節點    cur = self.__head    pre = None    while cur.next != self.__head:      if cur.item == item:        # 先判斷此結點是否是頭節點        if cur == self.__head:          # 頭節點的情況          # 找尾節點          rear = self.__head          while rear.next != self.__head:            rear = rear.next          self.__head = cur.next          rear.next = self.__head        else:          # 中間節點          pre.next = cur.next        return      else:        pre = cur        cur = cur.next    # 退出循環，cur指向尾節點    if cur.item == item:      if cur == self.__head:        # 鏈表只有一個節點        self.__head = None      else:        # pre.next = cur.next        pre.next = self.__head  def search(self, item):    """查找節點是否存在"""    if self.is_empty():      return False    cur = self.__head    if cur.item == item:      return True    while cur.next != self.__head:      cur = cur.next      if cur.item == item:        return True    return Falseif __name__ == "__main__":  ll = SinCycLinkedlist()  ll.add(1)  ll.add(2)  ll.append(3)  ll.insert(2, 4)  ll.insert(4, 5)  ll.insert(0, 6)  print("length:", ll.length())  ll.travel()  print(ll.search(3))  print(ll.search(7))  ll.remove(1)  print("length:", ll.length())  ll.travel()