# -*- coding:utf-8 -*-
#! python3
class Node():
  def __init__(self,item):
    #初始化這個(gè)節(jié)點(diǎn)，值和下一個(gè)指向
    self.item = item
    self.next = None
class SingleLinklist():
  def __init__(self):
    #初始化這個(gè)單鏈表的頭指針為空
    self._head = None
  def length(self):
    #獲取這個(gè)鏈表的長(zhǎng)度
    count = 0
    cur = self._head
    while cur != None:
      count+=1
      cur = cur.next
    return count
  def is_empty(self):
    """判斷是否為空"""
    return self._head == None
  def add(self,item):
    """在頭部添加元素"""
    node = Node(item)
    node.next = self._head
    self._head = node
  def append(self,item):
    """在尾部添加元素"""
    cur = self._head
    node = Node(item)
    while cur != None:
      cur = cur.next
    cur.next = node
  def insert(self,pos,item):
    """在選定的位置添加元素"""
    cur = self._head
    node = Node(item)
    count = 0
    if pos <= 0:
      self.add(item)
    elif pos > (self.length()-1):
      self.append(item)
    else:
      while count < (pos -1):
        count+=1
        cur = cur.next
      node.next = cur.next
      cur.next = node
  def travel(self):
    """遍歷整個(gè)鏈表"""
    cur = self._head
    while cur != None:
      print(cur.item,end=" ")
      cur = cur.next
    print(" ")
  def remove(self,item):
    """刪除鏈表"""
    cur = self._head
    pre =None
    while cur != None:
      if cur.item == item:
        if not pre:
          self._head = cur.next
          break
        else:
          pre.next = cur.next
      else:
        pre = cur #
        cur = cur.next
  def search(self,item):
    """查找某個(gè)節(jié)點(diǎn)"""
    cur = self._head
    while cur != None:
      if cur.item == item:
        print("找到這個(gè)元素了")
        return True
      cur = cur.next
    print("抱歉沒(méi)有這個(gè)元素")
    return False
singlistdemo = SingleLinklist()
singlistdemo.add(1)
singlistdemo.add(2)
singlistdemo.add(65)
singlistdemo.insert(2,77)
singlistdemo.insert(1,66)
singlistdemo.insert(0,66)
print(singlistdemo.length())
singlistdemo.travel()
singlistdemo.remove(1)
singlistdemo.travel()
singlistdemo.search(65)