leetcode -- Partition List -- 常见题型重点

class Solution(object):
def partition(self, head, x):
"""
:type head: ListNode
:type x: int
:rtype: ListNode
"""
dummy1, dummy2 = ListNode(0), ListNode(0)

p1, p2 = dummy1,dummy2
p1.next, p2.next = None, None
i = head

while i:
tmp = i.next
if i.val < x:
p1.next = i
p1 = p1.next
p1.next = None
else:
p2.next = i
p2 = p2.next
p2.next = None

i = tmp

p1.next = dummy2.next
return dummy1.next