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* Retranslate the complete English edition from Simplified Chinese * Polish three English explanations after reader-focused review
43 lines
1.3 KiB
Python
43 lines
1.3 KiB
Python
"""
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File: binary_tree_bfs.py
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Created Time: 2022-12-20
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Author: a16su (lpluls001@gmail.com)
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"""
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import sys
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from pathlib import Path
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sys.path.append(str(Path(__file__).parent.parent))
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from modules import TreeNode, list_to_tree, print_tree
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from collections import deque
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def level_order(root: TreeNode | None) -> list[int]:
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"""Level-order traversal"""
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# Initialize a queue and enqueue the root
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queue: deque[TreeNode] = deque()
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queue.append(root)
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# Initialize a list to store the traversal sequence
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res = []
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while queue:
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node: TreeNode = queue.popleft() # Dequeue from the queue
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res.append(node.val) # Store the node value
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if node.left is not None:
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queue.append(node.left) # Enqueue the left child
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if node.right is not None:
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queue.append(node.right) # Enqueue the right child
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return res
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"""Driver code"""
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if __name__ == "__main__":
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# Initialize the binary tree
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# Use a helper function that builds a binary tree directly from an array
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root: TreeNode = list_to_tree(arr=[1, 2, 3, 4, 5, 6, 7])
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print("\nInitialize the binary tree\n")
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print_tree(root)
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# Level-order traversal
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res: list[int] = level_order(root)
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print("\nNode sequence from level-order traversal = ", res)
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