Python/data_structures/binary_tree/is_sum_tree.py at master · TheAlgorithms/Python · GitHub

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"""
Is a binary tree a sum tree where the value of every non-leaf node is equal to the sum
of the values of its left and right subtrees?
https://www.geeksforgeeks.org/check-if-a-given-binary-tree-is-sumtree
"""

from __future__ importannotations

fromcollections.abcimportIterator
fromdataclassesimportdataclass


@dataclass
classNode:
data: int
left: Node|None=None
right: Node|None=None

def__iter__(self) ->Iterator[int]:
"""
 >>> root = Node(2)
 >>> list(root)
 [2]
 >>> root.left = Node(1)
 >>> tuple(root)
 (1, 2)
 """
ifself.left:
yieldfromself.left
yieldself.data
ifself.right:
yieldfromself.right

def__len__(self) ->int:
"""
 >>> root = Node(2)
 >>> len(root)
 1
 >>> root.left = Node(1)
 >>> len(root)
 2
 """
returnsum(1for_inself)

@property
defis_sum_node(self) ->bool:
"""
 >>> root = Node(3)
 >>> root.is_sum_node
 True
 >>> root.left = Node(1)
 >>> root.is_sum_node
 False
 >>> root.right = Node(2)
 >>> root.is_sum_node
 True
 """
ifnotself.leftandnotself.right:
returnTrue# leaf nodes are considered sum nodes
left_sum=sum(self.left) ifself.leftelse0
right_sum=sum(self.right) ifself.rightelse0
returnall(
 (
self.data==left_sum+right_sum,
self.left.is_sum_nodeifself.leftelseTrue,
self.right.is_sum_nodeifself.rightelseTrue,
 )
 )


@dataclass
classBinaryTree:
root: Node

def__iter__(self) ->Iterator[int]:
"""
 >>> list(BinaryTree.build_a_tree())
 [1, 2, 7, 11, 15, 29, 35, 40]
 """
returniter(self.root)

def__len__(self) ->int:
"""
 >>> len(BinaryTree.build_a_tree())
 8
 """
returnlen(self.root)

def__str__(self) ->str:
"""
 Returns a string representation of the inorder traversal of the binary tree.

 >>> str(list(BinaryTree.build_a_tree()))
 '[1, 2, 7, 11, 15, 29, 35, 40]'
 """
returnstr(list(self))

@property
defis_sum_tree(self) ->bool:
"""
 >>> BinaryTree.build_a_tree().is_sum_tree
 False
 >>> BinaryTree.build_a_sum_tree().is_sum_tree
 True
 """
returnself.root.is_sum_node

@classmethod
defbuild_a_tree(cls) ->BinaryTree:
r"""
 Create a binary tree with the specified structure:
 11
 / \
 2 29
 / \ / \
 1 7 15 40
 \
 35
 >>> list(BinaryTree.build_a_tree())
 [1, 2, 7, 11, 15, 29, 35, 40]
 """
tree=BinaryTree(Node(11))
root=tree.root
root.left=Node(2)
root.right=Node(29)
root.left.left=Node(1)
root.left.right=Node(7)
root.right.left=Node(15)
root.right.right=Node(40)
root.right.right.left=Node(35)
returntree

@classmethod
defbuild_a_sum_tree(cls) ->BinaryTree:
r"""
 Create a binary tree with the specified structure:
 26
 / \
 10 3
 / \ \
 4 6 3
 >>> list(BinaryTree.build_a_sum_tree())
 [4, 10, 6, 26, 3, 3]
 """
tree=BinaryTree(Node(26))
root=tree.root
root.left=Node(10)
root.right=Node(3)
root.left.left=Node(4)
root.left.right=Node(6)
root.right.right=Node(3)
returntree


if__name__=="__main__":
fromdoctestimporttestmod

testmod()
tree=BinaryTree.build_a_tree()
print(f"{tree} has {len(tree)} nodes and {tree.is_sum_tree=}.")
tree=BinaryTree.build_a_sum_tree()
print(f"{tree} has {len(tree)} nodes and {tree.is_sum_tree=}.")