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Made binary tree memory-friendly using generators based travels. Fixes (#9208)

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#8725
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aryan1165 2023-10-01 14:13:48 +05:30 committed by GitHub
parent fbbbd5db05
commit eaa87bd791
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1 changed files with 34 additions and 22 deletions
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56
data_structures/binary_tree/binary_tree_traversals.py
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@ -1,12 +1,12 @@
# https://en.wikipedia.org/wiki/Tree_traversal
from __future__ import annotations from __future__ import annotations
from collections import deque from collections import deque
from collections.abc import Sequence from collections.abc import Generator, Sequence
from dataclasses import dataclass from dataclasses import dataclass
from typing import Any from typing import Any
# https://en.wikipedia.org/wiki/Tree_traversal
@dataclass @dataclass
class Node: class Node:
data: int data: int
@ -31,44 +31,56 @@ def make_tree() -> Node | None:
return tree return tree
def preorder(root: Node | None) -> list[int]: def preorder(root: Node | None) -> Generator[int, None, None]:
""" """
Pre-order traversal visits root node, left subtree, right subtree. Pre-order traversal visits root node, left subtree, right subtree.
>>> preorder(make_tree()) >>> list(preorder(make_tree()))
[1, 2, 4, 5, 3] [1, 2, 4, 5, 3]
""" """
return [root.data, *preorder(root.left), *preorder(root.right)] if root else [] if not root:
return
yield root.data
yield from preorder(root.left)
yield from preorder(root.right)
def postorder(root: Node | None) -> list[int]: def postorder(root: Node | None) -> Generator[int, None, None]:
""" """
Post-order traversal visits left subtree, right subtree, root node. Post-order traversal visits left subtree, right subtree, root node.
>>> postorder(make_tree()) >>> list(postorder(make_tree()))
[4, 5, 2, 3, 1] [4, 5, 2, 3, 1]
""" """
return postorder(root.left) + postorder(root.right) + [root.data] if root else [] if not root:
return
yield from postorder(root.left)
yield from postorder(root.right)
yield root.data
def inorder(root: Node | None) -> list[int]: def inorder(root: Node | None) -> Generator[int, None, None]:
""" """
In-order traversal visits left subtree, root node, right subtree. In-order traversal visits left subtree, root node, right subtree.
>>> inorder(make_tree()) >>> list(inorder(make_tree()))
[4, 2, 5, 1, 3] [4, 2, 5, 1, 3]
""" """
return [*inorder(root.left), root.data, *inorder(root.right)] if root else [] if not root:
return
yield from inorder(root.left)
yield root.data
yield from inorder(root.right)
def reverse_inorder(root: Node | None) -> list[int]: def reverse_inorder(root: Node | None) -> Generator[int, None, None]:
""" """
Reverse in-order traversal visits right subtree, root node, left subtree. Reverse in-order traversal visits right subtree, root node, left subtree.
>>> reverse_inorder(make_tree()) >>> list(reverse_inorder(make_tree()))
[3, 1, 5, 2, 4] [3, 1, 5, 2, 4]
""" """
return ( if not root:
[*reverse_inorder(root.right), root.data, *reverse_inorder(root.left)] return
if root yield from reverse_inorder(root.right)
else [] yield root.data
) yield from reverse_inorder(root.left)
def height(root: Node | None) -> int: def height(root: Node | None) -> int:
@ -178,10 +190,10 @@ def main() -> None: # Main function for testing.
root = make_tree() root = make_tree()
# All Traversals of the binary are as follows: # All Traversals of the binary are as follows:
print(f"In-order Traversal: {inorder(root)}") print(f"In-order Traversal: {list(inorder(root))}")
print(f"Reverse In-order Traversal: {reverse_inorder(root)}") print(f"Reverse In-order Traversal: {list(reverse_inorder(root))}")
print(f"Pre-order Traversal: {preorder(root)}") print(f"Pre-order Traversal: {list(preorder(root))}")
print(f"Post-order Traversal: {postorder(root)}", "\n") print(f"Post-order Traversal: {list(postorder(root))}", "\n")
print(f"Height of Tree: {height(root)}", "\n") print(f"Height of Tree: {height(root)}", "\n")