python實現鍊錶與反轉

鍊錶記錄了頭節點與尾節點，是為了方便末尾新增時，不在遍歷鍊錶而設定的。反轉的思想是設定乙個前驅節點為none，首節點指向none，下乙個節點指向前乙個節點即可。

class

node
(object):
def__init__
(self, data=
none
,next
=none):
self.data = data
self.
next
=next
def__str__
(self)
:return f''
class
linkedlist
(object):
def__init__
(self)
:        self.head =
none
self.last =
none
defis_empty
(self):if
not self.head:
return
true
def(self, data)
:if self.is_empty():
self.head = node(data)
self.last = self.head
else
:            self.last.
next
= node(data)
self.last = self.last.
next
# cur = self.head
# while cur.next:
#     cur = cur.next
# cur.next = node(data)
defiter_node
(self)
:        cur = self.head
while cur:
print
(cur)
cur = cur.
next
deflast_node
(self)
:return self.last
defreverse
(self)
:# 前驅節點
pre =
none
# 當前節點
cur = self.head
# 頭尾節點交換
self.head, self.last = self.last, self.head
while cur:
# 記錄後驅節點
tmp = cur.
next
# 後驅節點指向前驅節點
cur.
next
= pre
# 當前節點成為前驅節點
pre = cur
cur = tmp
# a -> b -> c -> d
l = linkedlist(
)'a'
)'b'
)'c'
)'d'
)l.iter_node(
)l.reverse(
)l.iter_node(
)# d -> c -> b -> a

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