话不多说，就是开始练习，因为之前编程的经验比较少，怎么办，就像马化腾一样，先抄袭，只有抄袭完成了之后，你才会获得你自己的知识
总体思路是先抄袭，再领悟。最后一定要自己默写打一次。不然没印象
案例1：求最长的回文数

class Solution:def longestPalindrome(self, s: str) -> str:def huiwenshu(s, l, r):while l >= 0 and r < len(s) and s[l] == s[r]:l -= 1r += 1return s[l + 1:r]res = ''for i in range(len(s)):sub1 = huiwenshu(s, i, i)sub2 = huiwenshu(s, i, i + 1)res = sub1 if len(sub1) > len(res) else resres = sub2 if len(sub2) > len(res) else resreturn resa=Solution()
f=a.longestPalindrome('abcdcda')
print(f)

案例二

class Solution:def isPalindrome(self, x: int) -> bool:return str(x) == str(x)[::-1]

案例三：

class Solution:def mySqrt(self, x: int) -> int:left,right = 0,xwhile left <= right:mid = (left + right)//2if mid * mid == x:return midelif mid * mid > x:if (mid-1)*(mid-1) <= x:return mid-1right = mid -1else:if (mid+1) * (mid+1) > x:return midleft = mid + 1return left

class Solution: def addStrings(self, num1: str, num2: str) -> str: return str(int(num1)+int(num2))

class Solution:
def findTheDifference(self, s: str, t: str) -> str:
res = 0
for i in s+t:
res ^= ord(i)
return chr(res)

`# Definition for a binary tree node.

class TreeNode:

def init(self, val=0, left=None, right=None):

self.val = val

self.left = left

self.right = right

class Solution:
def isSymmetric(self, root: Optional[TreeNode]) -> bool:
if not root:
return True
def jugde(left,right):
if not left and not right:
return True
if not left or not right:
return False
if left.val != right.val:
return False
return jugde(left.left,right.right) and jugde(left.right, right.left)
return jugde(root.left, root.right)`

class Solution:def isPalindrome(self, s: str) -> bool:s1=''.join(filter(str.isalnum, s)).lower()return s1==s1[::-1]