return None, None
if node.left:
node.left.right, node.left.left = dfs(node.left)
if node.right:
node.right.right, node.right.left = dfs(node.right)
return node.left, node.right
if not root:
return
root.right, root.left = dfs(root)
return root
if __name__ == '__main__':
root = TreeNode(4)
left = TreeNode(2)
right = TreeNode(7)
root.left = left
root.right = right
leftleft = TreeNode(1)
leftright = TreeNode(3)
left.left = leftleft
left.right = leftright
rightleft = TreeNode(6)
rightright = TreeNode(9)
right.left = rightleft
right.right = rightright
midOrder(root)
root = Solution().invertTree(root)
midOrder(root)
midOrder(Solution().invertTree(None))
return dfs(0, len(inorder) - 1, 0, len(postorder) - 1)
class Solution:
def buildTree(self, inorder, postorder):
"""
:type inorder: List[int]
:type postorder: List[int]
:rtype: TreeNode
"""
def build(mark):
if inorder and inorder[-1] != mark:
root = TreeNode(postorder.pop())
root.right = build(root.val)
inorder.pop()
root.left = build(mark)
return root
return None
return build(None)
if __name__ == '__main__':
# preorder = [3, 9, 20, 15, 7]
preorder = [3, 2, 1, 4]
# inorder = [9, 3, 15, 20, 7]
inorder = [1, 2, 3, 4]
root = Solution().buildTree(preorder, inorder)
from common.tree import midOrder
midOrder(root)
if not t2:
return t1
t1.val = t1.val + t2.val
t1.left = self.mergeTrees(t1.left, t2.left)
t1.right = self.mergeTrees(t1.right, t2.right)
return t1
if __name__ == '__main__':
t1root = TreeNode(1)
t1left = TreeNode(3)
t1right = TreeNode(2)
t1root.left = t1left
t1root.right = t1right
t1leftleft = TreeNode(5)
t1left.left = t1leftleft
t2root = TreeNode(2)
t2left = TreeNode(1)
t2right = TreeNode(3)
t2root.left = t2left
t2root.right = t2right
t2leftright = TreeNode(4)
t2rightright = TreeNode(7)
t2left.right = t2leftright
t2right.right = t2rightright
t = Solution().mergeTrees(t1root, t2root)
midOrder(t)