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054-tree-serializer.py
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153 lines (110 loc) · 3.82 KB
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from collections import deque
class TreeNode(object):
def __init__(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right
def insert_left(self, value):
self.left = TreeNode(value)
return self.left
def insert_right(self, value):
self.right = TreeNode(value)
return self.right
def level_order_traversal(node: TreeNode):
if not node:
return None
nodes = deque()
nodes.append(node)
while nodes:
for _ in range(len(nodes)):
n = nodes.popleft()
print(str(n.val) + '->', end='')
nodes.append(n.left) if n.left else None
nodes.append(n.right) if n.right else None
print('')
return None
class Codec:
def serialize(self, root: TreeNode) -> str:
if not root:
return ""
serialization = []
nodes = deque()
nodes.append(root)
while nodes:
level_nodes = []
at_least_one_node_in_level = False
for _ in range(len(nodes)):
n = nodes.popleft()
if n:
at_least_one_node_in_level = True
level_nodes.append(n.val)
nodes.append(n.left)
nodes.append(n.right)
else:
level_nodes.append(str(None))
if at_least_one_node_in_level:
serialization.extend(level_nodes)
serialized = ','.join(map(str, serialization))
return serialized
def deserialize(self, data: str) -> TreeNode:
if not data:
return
deserialized, deserialized_index = data.split(','), 0
root = TreeNode(int(deserialized[deserialized_index]))
deserialized_index += 1
nodes = deque()
nodes.append(root)
while nodes and deserialized_index < len(deserialized):
n = nodes.popleft()
left = deserialized[deserialized_index]
deserialized_index += 1
if left != str(None):
n.left = TreeNode(int(left))
nodes.append(n.left)
right = deserialized[deserialized_index]
deserialized_index += 1
if right != str(None):
n.right = TreeNode(int(right))
nodes.append(n.right)
return root
def serialize_preorder(self, root: TreeNode) -> str:
if not root:
return ''
def rserialize(node: TreeNode):
if not node:
serialization.append(str(None))
return
serialization.append(node.val)
rserialize(node.left)
rserialize(node.right)
serialization = deque()
rserialize(root)
return ','.join(map(str, serialization))
def deserialize_preorder(self, data: str) -> TreeNode:
if not data:
return None
def rdeserialize(deserialized_values: deque) -> TreeNode:
v = deserialized_values.popleft()
if v == str(None):
return
node = TreeNode(int(v))
node.left = rdeserialize(deserialized_values)
node.right = rdeserialize(deserialized_values)
return node
deserialized = deque(data.split(','))
root = rdeserialize(deserialized)
return root
tree = TreeNode(1)
left = tree.insert_left(2)
right = tree.insert_right(3)
left.insert_left(1)
left_right = left.insert_right(3)
left_right.insert_right(3).insert_left(2)
right.insert_left(4)
right.insert_right(5)
level_order_traversal(tree)
codec = Codec()
level_order_traversal(codec.deserialize(codec.serialize(tree)))
codec.deserialize(codec.serialize(None))
level_order_traversal(codec.deserialize_preorder(
(codec.serialize_preorder(tree))))