51 lines
1.2 KiB
Markdown
51 lines
1.2 KiB
Markdown
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---
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title: Breadth-First Search
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localeTitle: 广度优先搜索
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---
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## 广度优先搜索
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让我们首先定义用于实现广度优先搜索算法的`Tree`类。
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```python
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class Tree:
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def __init__(self, x):
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self.val = x
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self.left = None
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self.right = None
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```
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广度优先搜索算法从树的根开始从一个级别移动到另一个级别。我们将为此使用`queue` 。
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```python
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def bfs(root_node):
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queue = [root_node]
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while queue:
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top_element = queue.pop()
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print("Node processed: ",top_element)
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if top_element.left:
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queue.append(top_element.left)
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if top_element.right:
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queue.append(top_element.right)
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```
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我们可以轻松修改上面的代码来打印每个节点的级别。
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```python
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def bfs(root_node):
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queue = [(root_node, 0)]
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while queue:
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top_element, level = queue.pop()
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print("Node processed: {} at level {}".format(top_element, level))
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if top_element.left:
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queue.append((top_element.left, level + 1))
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if top_element.right:
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queue.append((top_element.right, level + 1))
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```
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|复杂性|时间|空间| | ----- | ------ | ------ | | BFS | n | n |
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