python 如何实现dfs
时间: 2023-03-14 07:02:55 浏览: 121
Python 可以使用递归函数来实现深度优先搜索(DFS)算法。它将搜索树分解为两个部分:“发现”过程和“探索”过程。“发现”过程会找到新的可能有用的节点,而“探索”过程会递归地去搜索这些新发现的节点,以达到最终目标。
相关问题
用python实现dfs遍历
可以使用以下Python代码实现深度优先搜索(DFS)遍历:
def dfs(graph, start, visited=None):
if visited is None:
visited = set()
visited.add(start)
for next in graph[start] - visited:
dfs(graph, next, visited)
return visited
怎么样Python实现dfs和bfs爬行策略
在Python中,深度优先搜索(DFS,Depth First Search)和广度优先搜索(BFS,Breadth First Search)通常用于网络爬虫(Web Crawling)中的节点遍历。以下是简单的Python实现:
### 深度优先搜索(DFS)
```python
from collections import deque
def dfs(graph, start):
visited = set()
stack = [start]
while stack:
vertex = stack.pop() # 弹出栈顶元素
if vertex not in visited:
print(vertex) # 访问节点
visited.add(vertex)
# 添加未访问的邻居到栈顶
neighbors = graph[vertex] if isinstance(graph[vertex], list) else graph[vertex].neighbors
for neighbor in neighbors:
if neighbor not in visited:
stack.append(neighbor)
# 示例用法:
graph = {'A': ['B', 'C'], 'B': ['D', 'E'], 'C': ['F'], 'D': [], 'E': [], 'F': []}
dfs(graph, 'A')
```
### 广度优先搜索(BFS)
```python
from collections import deque
def bfs(graph, start):
visited = set()
queue = deque([start]) # 使用双端队列存储节点
while queue:
vertex = queue.popleft() # 弹出队首元素
if vertex not in visited:
print(vertex) # 访问节点
visited.add(vertex)
# 将未访问的邻居添加到队列尾部
neighbors = graph[vertex] if isinstance(graph[vertex], list) else graph[vertex].neighbors
for neighbor in neighbors:
if neighbor not in visited:
queue.append(neighbor)
# 示例用法:
graph = {'A': ['B', 'C'], 'B': ['D', 'E'], 'C': ['F'], 'D': [], 'E': [], 'F': []}
bfs(graph, 'A')
```
在这两个示例中,`graph`是一个表示网络结构的字典,其中键是节点名,值可以是列表(表示有向图)或包含邻居的属性(表示无向图)。`start`是开始遍历的起始节点。
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