def increasingBST(self, root: TreeNode, nxt: TreeNode = None) -> TreeNode:
if not root:
return nxt
head = self.increasingBST(root.left, root)
root.left = None
root.right = self.increasingBST(root.right, nxt)
return head
def deleteNode(self, root: TreeNode, key: int) -> TreeNode:
if root is None:
return root
if key < root.val:
root.left = self.deleteNode(root.left, key)
elif key > root.val:
root.right = self.deleteNode(root.right, key)
else: # found the key
if root.left is None:
return root.right
if root.right is None:
return root.left
min_val = self.findMin(root.right)
root.val = min_val
root.right = self.deleteNode(root.right, min_val)
return root
def build(xs: List[int], ubound: int) -> Optional[TreeNode]:
if not xs or xs[-1] > ubound:
return None
root = TreeNode(xs.pop())
root.left = build(xs, root.val)
root.right = build(xs, ubound)
return root
def pruneTreeV2(self, root: TreeNode) -> TreeNode:
if not root:
return None
root.left = self.pruneTree(root.left)
root.right = self.pruneTree(root.right)
if not root.left and not root.right and not root.val:
return None
return root
def pruneTreeV1(self, root: TreeNode) -> TreeNode:
def not_contain_1(root: TreeNode) -> bool:
if not root:
return True
if left_not_contain_1 := not_contain_1(root.left):
root.left = None
if right_not_contain_1 := not_contain_1(root.right):
root.right = None
def insertIntoBST(self, root: TreeNode, val: int) -> TreeNode:
if not root:
return TreeNode(val)
if val < root.val:
root.left = self.insertIntoBST(root.left, val)
else:
root.right = self.insertIntoBST(root.right, val)
return root
def treeToDoublyList(self, root: TreeNode) -> TreeNode:
if not root:
return None
lhead = self.treeToDoublyList(root.left)
rhead = self.treeToDoublyList(root.right)
# make root itself a single node DLL
root.left = root
root.right = root
return self.connect(self.connect(lhead, root), rhead)
def trimBST(self, root: TreeNode, low: int, high: int) -> TreeNode:
if not root:
return root
if root.val < low:
return self.trimBST(root.right, low, high)
elif root.val > high:
return self.trimBST(root.left, low, high)
else:
root.left = self.trimBST(root.left, low, root.val)
root.right = self.trimBST(root.right, root.val, high)
return root
def _deserialize(buffer: List[str], lower: int,
upper: int) -> "TreeNode":
if len(buffer) == 0:
return None
if buffer[0] < lower or buffer[0] > upper:
return None
val = buffer.pop(0)
root = TreeNode(val)
root.left = _deserialize(buffer, lower, val)
root.right = _deserialize(buffer, val, upper)
return root
def addOneRow(self,
root: TreeNode,
v: int,
d: int,
left: bool = True) -> TreeNode:
if d == 1:
nroot = TreeNode(v, root if left else None, None if left else root)
return nroot
if not root:
return root
root.left = self.addOneRow(root.left, v, d - 1, True)
root.right = self.addOneRow(root.right, v, d - 1, False)
return root
def helper(node: TreeNode) -> Tuple[TreeNode, TreeNode]:
if not node:
return None, None
if node.left:
head, ltail = helper(node.left)
ltail.right, node.left = node, None
else:
head = node
if node.right:
node.right, rtail = helper(node.right)
else:
rtail = node
return head, rtail