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
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 bstToGst(self, root: TreeNode) -> TreeNode:
if root:
self.bstToGst(root.right)
self.total += root.val
root.val = self.total
self.bstToGst(root.left)
return root
def str2tree(self, s: str) -> TreeNode:
def is_number(ss):
for cc in ss:
if not cc.isnumeric() and not cc == "-":
return False
return True
if not s:
return None
lst = []
for ch in s:
if is_number(ch):
if lst and is_number(lst[-1]):
lst[-1] += ch
else:
lst.append(ch)
else:
lst.append(ch)
print(lst)
stack = [TreeNode(int(lst[0]))]
i = 1
while i < len(lst):
if lst[i] == "(":
new = TreeNode(int(lst[i + 1]))
if not stack[-1].left:
stack[-1].left = new
stack.append(new)
else:
stack[-1].right = new
stack.append(new)
i += 2
elif lst[i] == ")":
stack.pop()
i += 1
return stack[0]
from LeetTool import TreeNode
from LeetTool import build_TreeNode
# Definition for a binary tree node.
class Solution:
def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode',
q: 'TreeNode') -> 'TreeNode':
pass
if __name__ == "__main__":
tree = build_TreeNode([3, 5, 1, 6, 2, 0, 8, None, None, 7, 4])
print(Solution().lowestCommonAncestor(tree, tree.left, tree.right)) # 3
tree = build_TreeNode([3, 5, 1, 6, 2, 0, 8, None, None, 7, 4])
print(Solution().lowestCommonAncestor(tree, tree.left,
tree.left.right.right)) # 5
tree = build_TreeNode([3, 5, 1, 6, 2, 0, 8, None, None, 7, 4])
node2 = TreeNode(10)
print(Solution().lowestCommonAncestor(tree, tree.left, node2)) # None