最长回文子串
def solution(s):
maxlen = 0
maxstr = ''
for i in range(len(s)):
for j in range(i+1):
if len(s[j:i+1])<=maxlen:#优化，减少循环
break
if s[j:i+1]==s[j:i+1][::-1] and len(s[j:i+1])>maxlen:
maxlen = len(s[j:i+1])
maxstr = s[j:i+1]
print(maxlen)
print(maxstr)
python合并有序链表
class ListNode:
def __init__(self, x):
self.val = x
self.next = None
class Solution:
def mergeTwoLists(self, l1, l2):
if l1 is None and l2 is None:
return None
new_list = ListNode(0)
pre = new_list
while l1 is not None and l2 is not None:
if l1.val < l2.val:
pre.next = l1
l1 = l1.next
else:
pre.next = l2
l2 = l2.next
pre = pre.next
if l1 is not None:
pre.next = l1
else:
pre.next = l2
return new_list.next
