python 实现链表的反转
从头开始遍历,每一个节点的next指向它的前一个节点。1
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44class ListNode:
def __init__(self,x):
self.val=x
self.next=None
def nonrecurse(head):
if head is None or head.next is None:
return head
pre = None
cur = head
h = head
while cur:
h=cur
tmp = cur.next
cur.next = pre
pre = cur
cur = tmp
return h
head = ListNode(1)
p1=ListNode(2)
p2=ListNode(3)
p3=ListNode(4)
head.next = p1
p1.next = p2
p2.next = p3
p=nonrecurse(head)
while p:
print p.val
p=p.next
head = ListNode(1)
p1=ListNode(2)
p2=ListNode(3)
p3=ListNode(4)
head.next = p1
p1.next = p2
p2.next = p3
p=nonrecurse(head)
while p:
print p.val
p=p.next