from typing import Optional
from binarytree import Node as TreeNode
from binarytree import build
def minCameraCover(root: Optional[TreeNode]) -> int:
res = 0
def dfs(node, hasParent):
if not node:
return -1
nonlocal res
left, right = dfs(node.left, True), dfs(node.right, True)
if left == -1 and right == -1:
if hasParent:
return 0
res += 1
return 2
if left == 0 or right == 0:
res += 1
return 2
if left == 2 or right == 2:
return 1
if hasParent:
return 0
res += 1
return 2
dfs(root, False)
return res
root = build([0, 0, None, 0, 0])
print(root)
print(minCameraCover(root)) # 1