请告诉我下面的 DFS 代码中哪些地方不正确。它给出的结果是正确的,但我不知道什么时候会失败。
graph1 = {
'A' : ['B','S'],
'B' : ['A'],
'C' : ['D','E','F','S'],
'D' : ['C'],
'E' : ['C','H'],
'F' : ['C','G'],
'G' : ['F','S'],
'H' : ['E','G'],
'S' : ['A','C','G']
}
visited = []
def dfs(graph,node):
global visited
if node not in visited:
visited.append(node)
for n in graph[node]:
dfs(graph,n)
dfs(graph1,'A')
print(visited)
输出:
['A', 'B', 'S', 'C', 'D', 'E', 'H', 'G', 'F']
我认为您的代码存在缩进问题。假设你的代码是这样的
graph1 = {
'A' : ['B','S'],
'B' : ['A'],
'C' : ['D','E','F','S'],
'D' : ['C'],
'E' : ['C','H'],
'F' : ['C','G'],
'G' : ['F','S'],
'H' : ['E','G'],
'S' : ['A','C','G']
}
visited = []
def dfs(graph,node):
global visited
if node not in visited:
visited.append(node)
for n in graph[node]:
dfs(graph,n)
dfs(graph1,'A')
print(visited)
我会说几件事:
再加上
更新代码:
graph1 = {
'A' : ['B','S'],
'B' : ['A'],
'C' : ['D','E','F','S'],
'D' : ['C'],
'E' : ['C','H'],
'F' : ['C','G'],
'G' : ['F','S'],
'H' : ['E','G'],
'S' : ['A','C','G']
}
def dfs(graph, node, visited):
if node not in visited:
visited.append(node)
for n in graph[node]:
dfs(graph,n, visited)
return visited
visited = dfs(graph1,'A', [])
print(visited)
无递归:
def dfs(graph, node):
访问 = [节点]
stack = [节点]
while stack:
node = stack[-1]
if node not in visited:
visited.extend(node)
remove_from_stack = True
for next in graph[node]:
if next not in visited:
stack.extend(next)
remove_from_stack = False
断开
if remove_from_stack:
stack.pop()
return visited
print (dfs(graph1, 'A'))
输出:
['A','B','S','C','D','E','H','G','F')
用 Python 实现 DFS
from collections import defaultdict
class Graph:
def __init__(self):
self.graph = defaultdict(list)
def addEdge(self, u, v):
self.graph[u].append(v)
def DFSUtil(self, v, visited):
visited[v]=True
print(v)
for i in self.graph[v]:
if visited[i] == False:
self.DFSUtil(i, visited)
def DFS(self):
V = len(self.graph)
visited = [False]*(V)
for i in range(V):
if visited[i] == False:
self.DFSUtil(i, visited)
# Driver code
# Create a graph given in the above diagram
g = Graph()
g.addEdge(0, 1)
g.addEdge(0, 2)
g.addEdge(1, 2)
g.addEdge(2, 0)
g.addEdge(2, 3)
g.addEdge(3, 3)
print("Following is Depth First Traversal")
g.DFS()
来源 :: [this][1]