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43 lines
1.2 KiB
Python
43 lines
1.2 KiB
Python
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"""
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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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"""層序走訪"""
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# 初始化佇列，加入根節點
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queue: deque[TreeNode] = deque()
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queue.append(root)
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# 初始化一個串列，用於儲存走訪序列
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res = []
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while queue:
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node: TreeNode = queue.popleft() # 隊列出隊
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res.append(node.val) # 儲存節點值
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if node.left is not None:
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queue.append(node.left) # 左子節點入列
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if node.right is not None:
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queue.append(node.right) # 右子節點入列
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return res
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"""Driver Code"""
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if __name__ == "__main__":
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# 初始化二元樹
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# 這裡藉助了一個從陣列直接生成二元樹的函式
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root: TreeNode = list_to_tree(arr=[1, 2, 3, 4, 5, 6, 7])
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print("\n初始化二元樹\n")
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print_tree(root)
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# 層序走訪
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res: list[int] = level_order(root)
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print("\n層序走訪的節點列印序列 = ", res)
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