第一次寫的,如果fast.next是none,那麼fast.next.next會報錯
def
middlenode
(self, head)
:# write your code here
i =0if head.val !=
none
: slow = head
fast = head
while fast.
next
.val !=
none
: slow = slow.
next
fast = fast.
next
while fast.
next
.val !=
none
: fast = fast.
next
return slow.val
else
:return
none
"""
definition of listnode
class listnode(object):
def __init__(self, val, next=none):
self.val = val
self.next = next
"""class
solution
:"""
@param head: the head of linked list.
@return: a middle node of the linked list
"""defmiddlenode
(self, head)
:# write your code here
ifnot head.
next
:return
none
else
: slow = head
fast = head
while fast.
next
: slow = slow.
next
fast = fast.
next
while fast.
next
: fast = fast.
next
break
return
(slow)
"""
definition of listnode
class listnode(object):
def __init__(self, val, next=none):
self.val = val
self.next = next
"""class
solution
:"""
@param head: the head of linked list.
@return: a middle node of the linked list
"""defmiddlenode
(self, head)
:# write your code here
ifnot head:
return
none
else
: slow = head
fast = head
while fast.
next
: fast = fast.
next
if fast.
next
: slow = slow.
next
fast = fast.
next
return
(slow)
檢視別人的寫法，先判斷fast.next，用and連線判斷fast.next.next。一條就搞定。
class
solution
:"""
@param head: the head of linked list.
@return: a middle node of the linked list
"""defmiddlenode
(self, head)
:# write your code here
ifnot head:
return
none
else
: slow,fast = head,head
while fast.
next
and fast.
next
.next
: slow = slow.
next
fast= fast.
next
.next
return slow
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