def sortedArrayToBST(self, nums):
"""
:type nums: List[int]
:rtype: TreeNode
"""
if not nums:
return None
mid = (len(nums) - 1) >> 1
root = TreeNode(nums[mid])
root.left = self.sortedArrayToBST(nums[:mid])
root.right = self.sortedArrayToBST(nums[mid + 1:])
return root
def reConstructBinaryTree2(self, tin, post):
"""根据中序遍历序列和后序遍历序列构建二叉树"""
if len(tin) == 0 or len(post) == 0:
return None
if len(tin) == 1:
return TreeNode(tin[0])
else:
flag = TreeNode(post[-1])
index = tin.index(post[-1])
flag.left = self.reConstructBinaryTree2(tin[:index], post[:index])
flag.right = self.reConstructBinaryTree2(tin[index + 1:],
post[index:-1])
return flag
def reConstructBinaryTree1(self, pre, tin):
"""根据先序遍历序列和中序遍历序列构建二叉树"""
if len(pre) == 0 or len(tin) == 0:
return None
if len(pre) == 1:
return TreeNode(pre[0])
else:
flag = TreeNode(pre[0])
index = tin.index(pre[0])
flag.left = self.reConstructBinaryTree1(pre[1:index + 1],
tin[:index])
flag.right = self.reConstructBinaryTree1(pre[index + 1:],
tin[index + 1:])
return flag
