def test_binarytree_0001(self):
tree = TreeNode.from_list([0, None, 2])
assert tree.val == 0
assert tree.left is None
assert tree.right.val == 2
assert tree.right == TreeNode(2)
def test_binarytree_0002(self):
tree = TreeNode.from_list([1, None, 0, 0, 1], )
assert tree.val == 1
assert tree.left is None
assert tree.right.val == 0
assert tree.right.left == TreeNode(0)
assert tree.right.right == TreeNode(1)
def test_binarytree_0004(self):
tree = TreeNode.from_list([1, 2, None, 4, None, 5, 6], )
assert tree.val == 1
assert tree.left.val == 2
assert tree.right is None
assert tree.left.left.val == 4
assert tree.left.right is None
assert tree.left.left.left == TreeNode(5)
assert tree.left.left.right == TreeNode(6)
def main():
list1 = [5, 2, 8, 1, 3, 7, 9]
list2 = [4, 0, 6]
tree1 = TreeNode.list2tree(list1)
tree2 = TreeNode.list2tree(list2)
result = get_two_trees_inorder(tree1, tree2)
print(result)
def dfs(tree, val):
if tree is None:
pass
if val < tree.val:
if tree.left:
dfs(tree.left, val)
else:
tree.left = TreeNode(val)
if val > tree.val:
if tree.right:
dfs(tree.right, val)
else:
tree.right = TreeNode(val)
def test_to_list_middle_leaves(self):
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
root.left.right = TreeNode(4)
root.right.left = TreeNode(5)
self.assertListEqual(to_list(root), [1, 2, 3, None, 4, 5])
def recur(root, left, right):
if left > right: return # 递归终止
node = TreeNode(preorder[root]) # 建立根节点
i = dic[preorder[root]] # 划分根节点、左子树、右子树
node.left = recur(root + 1, left, i - 1) # 开启左子树递归
node.right = recur(i - left + root + 1, i + 1, right) # 开启右子树递归
return node # 回溯返回根节点
def deserialize(self, data):
if data == "[]": return
vals, i = data[1:-1].split(','), 1
root = TreeNode(int(vals[0]))
queue = collections.deque()
queue.append(root)
while queue:
node = queue.popleft()
if vals[i] != "null":
node.left = TreeNode(int(vals[i]))
queue.append(node.left)
i += 1
if vals[i] != "null":
node.right = TreeNode(int(vals[i]))
queue.append(node.right)
i += 1
return root
def insert(self, data):
if not self.tree:
self.tree = TreeNode(data)
return
p = self.tree
while p != None:
if data > p.val:
if p.right == None:
p.right = TreeNode(data)
return
p = p.right
else:
if p.left == None:
p.left = TreeNode(data)
return
p = p.left
def dfs(lpre, rpre, lin, rin):
#边界条件
if lpre > rpre: return None
if lpre == rpre:
return TreeNode(preorder[lpre])
#前序的第一个值是根节点
root = TreeNode(preorder[lpre])
#取出中序的根节点
idx = dic[root.val]
#递归左右子树
leftTree = dfs(lpre + 1, lpre + (idx - lin), lin, idx - 1)
rightTree = dfs(lpre + (idx - lin) + 1, rpre, idx + 1, rin)
#连回根节点
root.left = leftTree
root.right = rightTree
return root
def dfs(lpost, rpost, lin, rin):
#边界条件
if lpost > rpost: return None
if lpost == rpost:
return TreeNode(postorder[lpost])
#后序的最后一个值是根节点
root = TreeNode(postorder[rpost])
#取出中序的根节点
idx = dic[root.val]
#递归左右子树
leftTree = dfs(lpost, lpost + (idx - lin) - 1, lin, idx - 1)
rightTree = dfs(lpost + (idx - lin), rpost - 1, idx + 1, rin)
#连回根节点
root.left = leftTree
root.right = rightTree
return root
def main():
root1 = [5,2,8,1,3,7,9]
tree = TreeNode.list2tree(root1)
# result = tree2list(tree)
# print(result)
dfs(tree)
def list2BinaryTree(root: TreeNode, nums: List, i: int):
if i < len(nums):
if nums[i] == None: # 节点是空的时候 返回空
return None
else:
root = TreeNode(nums[i])
root.left = list2BinaryTree(root.left, nums, i * 2 + 1)
root.right = list2BinaryTree(root.right, nums, i * 2 + 2)
return root
return root
def main():
input_list = [
[5, 2, 8, 1, 3, 7, 9],
[2, 1, 3],
]
for lst in input_list:
tree = TreeNode.list2tree(lst)
result = get_inorder_iterative(tree)
print(f"{lst} -> {result}")
def pruneTree(self, root: TreeNode) -> TreeNode:
"""
prune the tree recursively!
"""
if root is None:
return None
if root.left is not None:
root.left = self.pruneTree(root.left)
if root.right is not None:
root.right = self.pruneTree(root.right)
if root.left is None and root.right is None:
if root.val == 0:
return None
else:
return root
return root
def constructMaximumBinaryTree(self, nums: List[int]) -> TreeNode:
if len(nums) == 1:
return TreeNode(nums[0])
if not nums:
return
max_index = nums.index(max(nums))
current_val = nums[max_index]
current_node = TreeNode(current_val)
left_nums = nums[:max_index]
right_nums = nums[max_index + 1:]
if left_nums:
current_node.left = self.constructMaximumBinaryTree(left_nums)
if right_nums:
current_node.right = self.constructMaximumBinaryTree(right_nums)
return current_node
def test_binarytree_0010(self):
with pytest.raises(TypeError):
TreeNode.from_list(None)
assert TreeNode.from_list([]) is None
assert TreeNode.from_list([None]) is None
assert TreeNode.from_list([1]) == TreeNode(1)
def mergeTrees(self, t1, t2):
"""
:type t1: TreeNode
:type t2: TreeNode
:rtype: TreeNode
"""
# Write your code here
if not t1 and not t2:
return None
elif t1 and t2:
result = TreeNode(t1.value + t2.value)
result.left = self.mergeTrees(t1.left, t2.left)
result.right = self.mergeTrees(t1.right, t2.right)
return result
else:
return t1 or t2
def helper(in_left, in_right):
# 如果这里没有节点构造二叉树了，就结束
if in_left > in_right:
return None
# 选择 post_idx 位置的元素作为当前子树根节点
val = postorder.pop()
root = TreeNode(val)
# 根据 root 所在位置分成左右两棵子树
index = idx_map[val]
# 构造右子树
root.right = helper(index + 1, in_right)
# 构造左子树
root.left = helper(in_left, index - 1)
return root
def listToTree(head):
# We just simply append everything to the left node
"""
Convert A sorted linkedlist into binary tree
>>> lst = Node(1, Node(2, Node(3, Node(4))))
>>> tree = listToTree(lst)
>>> tmp = []
>>> while tree is not None:
... tmp.append(tree.data)
... tree = tree.left
>>> tmp
[4, 3, 2, 1]
"""
rst = None
while head is not None:
rst = TreeNode(head.data, rst, None) # append to the left
head = head.next
return rst
def initNode() -> TreeNode:
a = TreeNode(1)
b = TreeNode(2)
c = TreeNode(3)
d = TreeNode(4)
e = TreeNode(5)
f = TreeNode(6)
g = TreeNode(7)
a.left = b
a.right = c
b.left = d
b.right = e
c.left = f
c.right = g
return a
from binarytree import BinaryTree, TreeNode
def get_binary_tree_size(node):
if node is None:
return 0
return 1 + get_binary_tree_size(node.left) + get_binary_tree_size(
node.right)
if __name__ == "__main__":
tree = BinaryTree(1)
tree.root.left = TreeNode(2)
tree.root.right = TreeNode(3)
tree.root.left.left = TreeNode(4)
tree.root.left.right = TreeNode(5)
print(get_binary_tree_size(tree.root))
def test_to_list_value(self):
root = TreeNode(1)
self.assertListEqual(to_list(root), [1])
def test_to_list_both_children(self):
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
self.assertListEqual(to_list(root), [1, 2, 3])
def test_to_list_missing_left(self):
root = TreeNode(1)
root.right = TreeNode(2)
self.assertListEqual(to_list(root), [1, None, 2])
def test_1():
sol = Solution()
tree = TreeNode.list2tree([1, 2, 3])
assert sol.findBottomLeftValue(tree) == 2
"""解法2：递归
- 时间复杂度：O(N)。其中 N 为二叉树节点数；每循环一轮排除一层，二叉搜索树的层数最小为 logN （满二叉树），最大为 N（退化为链表）。
- 空间复杂度：O(N)。最差情况下，递归深度达到 N ，使用 O(N) 大小的额外空间。
"""
# class Solution:
# def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
# if root.val < p.val and root.val < q.val:
# return self.lowestCommonAncestor(root.right, p, q)
# if root.val > p.val and root.val > q.val:
# return self.lowestCommonAncestor(root.left, p, q)
# return root
if __name__ == "__main__":
# root = [6,2,8,0,4,7,9,null,null,3,5]
root = TreeNode(6)
root.left = TreeNode(2)
root.right = TreeNode(8)
root.left.left = TreeNode(0)
root.left.right = TreeNode(4)
root.right.left = TreeNode(7)
root.right.right = TreeNode(9)
root.left.right.left = TreeNode(3)
root.left.right.right = TreeNode(5)
# p = 2
p = root.left
# q = 4
q = root.left.right
print(root)
print(Solution().lowestCommonAncestor(root, p, q)) # 2
"""解法1：递归法
- 时间复杂度：O(MN)。其中 M,N 分别为树 A 和树 B 的节点数量。
- 空间复杂度：O(M)。
"""
class Solution:
def isSubStructure(self, A: TreeNode, B: TreeNode) -> bool:
def recur(A, B):
if not B: return True
if not A or A.val != B.val: return False
return recur(A.left, B.left) and recur(A.right, B.right)
return bool(A and B) and (recur(A, B) or self.isSubStructure(
A.left, B) or self.isSubStructure(A.right, B))
if __name__ == "__main__":
A = TreeNode(3)
A.left = TreeNode(4)
A.right = TreeNode(5)
A.left.left = TreeNode(1)
A.left.right = TreeNode(2)
B = TreeNode(4)
B.left = TreeNode(1)
print(A, B)
print(Solution().isSubStructure(A, B))
from binarytree import Node as TreeNode
from typing import List
import collections
class Solution:
def levelOrder(self, root: TreeNode) -> List[List[int]]:
if not root: return []
res, queue = [], collections.deque()
queue.append(root)
while queue:
tmp = []
for _ in range(len(queue)):
node = queue.popleft()
tmp.append(node.val)
if node.left: queue.append(node.left)
if node.right: queue.append(node.right)
res.append(tmp)
return res
if __name__ == "__main__":
root = TreeNode(3)
root.left = TreeNode(9)
root.right = TreeNode(20)
root.right.left = TreeNode(15)
root.right.right = TreeNode(7)
print(root)
print(Solution().levelOrder(root))
def insertIntoBST(self, root: TreeNode, val: int) -> TreeNode:
def dfs(tree, val):
if tree is None:
pass
if val < tree.val:
if tree.left:
dfs(tree.left, val)
else:
tree.left = TreeNode(val)
if val > tree.val:
if tree.right:
dfs(tree.right, val)
else:
tree.right = TreeNode(val)
dfs(root, val)
return root
if __name__ == '__main__':
input_list = [(5, [4, 2, 7, 1, 3])]
sol = Solution()
for inp in input_list:
tree = TreeNode.list2tree(inp[1])
new_tree = sol.insertIntoBST(tree, inp[0])
new_tree.printTree_bfs()