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40 lines
1.2 KiB
Python
40 lines
1.2 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, os.path as osp
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sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
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from modules import *
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from collections import deque
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def level_order(root: TreeNode | None) -> list[int]:
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""" 层序遍历 """
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# 初始化队列，加入根结点
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queue: deque[TreeNode] = deque()
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queue.append(root)
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# 初始化一个列表，用于保存遍历序列
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res: list[int] = []
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while queue:
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node: TreeNode = queue.popleft() # 队列出队
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res.append(node.val) # 保存结点值
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if node.left is not None:
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queue.append(node.left) # 左子结点入队
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if node.right is not None:
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queue.append(node.right) # 右子结点入队
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return res
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""" Driver Code """
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if __name__ == "__main__":
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# 初始化二叉树
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# 这里借助了一个从数组直接生成二叉树的函数
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root: TreeNode = list_to_tree(arr=[1, 2, 3, 4, 5, 6, 7])
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print("\n初始化二叉树\n")
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print_tree(root)
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# 层序遍历
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res: list[int] = level_order(root)
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print("\n层序遍历的结点打印序列 = ", res)
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assert res == [1, 2, 3, 4, 5, 6, 7]
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