函數說明:
- 初始化;
- 判空;
- 求長度;
- 插入節點:頭插、尾插、隨機插入;
- 遍歷節點;
- 刪除節點;
- 查找節點(搜索節點);
代碼:
class Node(object):
def __init__(self, elem):
self.elem = elem
self.next = None
class SingleLinkList(object):
"""單向循環鏈表"""
def __init__(self, node = None):
self.__head = node
if node:
node.next = node
def is_empty(self):
"""鏈表是否爲空"""
return self.__head == None
def length(self):
if self.is_empty():
return 0
# 遊標用來遍歷節點
cur = self.__head
# 節點計數器,初始值影響while循環的判斷條件
counter = 1
while cur.next != self.__head :
counter += 1
cur = cur.next
return counter
def travel(self):
if self.is_empty():
return
cur = self.__head
while cur.next != self.__head:
print(cur.elem)
cur = cur.next
# 退出循環,cur指向尾節點,但尾節點的元素未打印
print(cur.elem)
def add(self, item):
"""鏈表頭部添加元素"""
# print("=====頭插法=====")
node = Node(item)
if self.is_empty():
self.__head = node
node.next = node
else:
# 遍歷尋找尾節點
cur = self.__head
while cur.next != self.__head:
cur = cur.next
# 退出循環,cur指向的就是尾節點
node.next = self.__head
self.__head = node
cur.next = node
def append(self, item):
"""鏈表尾部添加元素"""
node = Node(item)
# print("=====尾插法=====")
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
node.next = self.__head
cur.next = node
def insert(self, pos, item):
"""
指定位置添加元素
@pos: 從0開始 例:insert(2,100)
因爲不涉及尾部,所以不需要修改代碼。
"""
if pos <= 0 :
self.add(item)
elif pos > (self.length() - 1):
self.append(item)
else:
node = Node(item)
pre = self.__head
count = 0
while count < (pos - 1):
pre = pre.next
count += 1
# 當循環退出後,pre指向pos-1位置
node.next = pre.next
pre.next = node
def search(self, item):
"""查找節點是否存在"""
if self.is_empty(): # 判斷特殊情況
return False
cur = self.__head
while cur.next != self.__head: # 修改條件,但丟了尾節點
if cur.elem == item:
return True
else:
cur = cur.next
# 退出循環,cur指向的就是尾節點
if cur.elem == elem:
return True
return False
# 難度係數高
def remove(self, item):
if self.is_empty():
return
cur = self.__head
pre = None
while cur.next != self.__head: # 修改條件
if cur.elem == item:
# 先判斷此節點是否爲頭節點
if cur == self.__head:
# 頭節點
# 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 # break
else: # 遊標移動
pre = cur
cur = cur.next
# 退出循環,cur指向尾節點
if cur.elem == 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