def splitBST(self, root: TreeNode, V: int) -> List[TreeNode]:
if not root:
return [None, None]
if V < root.val:
left, right = self.splitBST(root.left, V)
root.left = right
return [left, root]
elif root.val < V:
left, right = self.splitBST(root.right, V)
root.right = left
return [root, right]
else:
right = root.right
root.right = None
return [root, right]
def convertBiNode(self, root: TreeNode, bigger=None) -> TreeNode:
if root:
# 处理当前节点
left, right = root.left, root.right
root.left = None
# 处理当前节点的右侧节点
if right:
root.right = self.convertBiNode(right, bigger)
else:
root.right = bigger
if left:
return self.convertBiNode(left, root)
else:
return root
def dfs(self, lst, l, r):
if l > r:
return None
if l == r:
return TreeNode(lst[l])
else:
m = (l + r) // 2
root = TreeNode(lst[m])
root.left = self.dfs(lst, l, m - 1)
root.right = self.dfs(lst, m + 1, r)
return root
def upsideDownBinaryTree(self, root: TreeNode) -> TreeNode:
if not root:
return None
ans = TreeNode(root.val)
while root.left:
node = TreeNode(root.left.val)
node.right = ans
node.left = root.right
ans = node
root = root.left
return ans
def encode(self, root: 'Node') -> TreeNode:
# 处理空树的情况
if not root:
return None
# 递归处理
head = TreeNode(root.val)
head.right = TreeNode(None)
p = head.right
if root.children:
for c in root.children:
p.left = self.encode(c)
p = p.left
return head