1. class Node(object):
    2.     """单个节点 """
    3.     def __init__(self, elem):
    4.         # 该节点存放的数据
    5.         self.elem = elem
    6.         # 指向下个节点的标识
    7.         self.next = None
    10. class SingleLinkList(object):
    11.     """单链表"""
    12.     def __init__(self, node=None):
    13.         self.__head = node
    15.     def is_empty(self):
    16.         """判断是否为空"""
    17.         return self.__head is None
    19.     def length(self):
    20.         """求长度"""
    21.         # cur游标，用来移动遍历节点
    22.         cur = self.__head
    23.         # count记录数量
    24.         count = 0
    25.         while cur is not None:
    26.             count += 1
    27.             cur = cur.next
    28.         return count
    30.     def travel(self):
    31.         """遍历"""
    32.         cur = self.__head
    33.         while cur is not None:
    34.             print(cur.elem, end=" ")
    35.             cur = cur.next
    37.     def add(self, item):
    38.         """头部添加元素，头插法"""
    39.         node = Node(item)
    40.         node.next = self.__head
    41.         self.__head = node
    43.     def append(self, item):
    44.         """尾部添加元素，尾插发"""
    45.         node = Node(item)
    46.         if self.is_empty():
    47.             self.__head = node
    48.         else:
    49.             cur = self.__head
    50.             while cur.next is not None:
    51.                 cur = cur.next
    52.             cur.next = node
    54.     def insert(self, pos, item):
    55.         """指定位置添加元素
    56.         :param item:节点数据
    57.         :param pos:插入位置，从0开始
    58.         """
    59.         if pos <= 0:
    60.             self.add(item)
    61.         elif pos > (self.length() - 1):
    62.             self.append(item)
    63.         else:
    64.             node = Node(item)
    65.             pre = self.__head
    66.             count = 0
    67.             while count < (pos - 1):
    68.                 pre = pre.next
    69.                 count += 1
    70.             # 当循环退出后，pre指向pos-1位置
    71.             node.next = pre.next
    72.             pre.next = node
    74.     def remove(self, item):
    75.         """删除指定元素"""
    76.         pre = None
    77.         cur = self.__head
    78.         while cur is not None:
    79.             if cur.elem == item:
    80.                 # 先判断此节点是否是头节点
    81.                 if cur == self.__head:
    82.                     self.__head == cur.next
    83.                 else:
    84.                     pre.next = cur.next
    85.                 return True
    86.             else:
    87.                 pre = cur
    88.                 cur = cur.next
    89.         return False
    91.     def search(self, item):
    92.         """查看节点是否存在"""
    93.         cur = self.__head
    94.         while cur is not None:
    95.             if cur.elem == item:
    96.                 return True
    97.             else:
    98.                 cur = cur.next
    99.         return False