738. 单调递增的数字

发现第一位变小了其他的迅速变9

python">class Solution:def monotoneIncreasingDigits(self, n: int) -> int:strn=list(str(n))for i in range(len(strn)-1,0,-1):if strn[i-1]>strn[i]:strn[i-1]=str(int(strn[i-1])-1)for j in range(i,len(strn)):strn[j]='9'return int(''.join(strn))

968. 监控二叉树

res是list才能传对象

python"># 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 minCameraCover(self, root: Optional[TreeNode]) -> int:res=[0]if self.tree(root,res)==0:res[0]+=1return res[0]def tree(self,cur,res):if not cur:return 2left=self.tree(cur.left,res)right=self.tree(cur.right,res)if left==2 and right==2:return 0elif left==0 or right==0:res[0]+=1return 1# if left==1 or right==1:else:return 2