python数据结构之图的实现方法

python数据结构之图的实现方法

本文实例讲述了python数据结构之图的实现方法。分享给大家供大家参考。具体如下：

下面简要的介绍下：

比如有这么一张图：



    A
-> B

    A
-> C

    B
-> C

    B
-> D

    C
-> D

    D
-> C

    E
-> F

    F
-> C



可以用字典和列表来构建  
 

graph = {'A': ['B', 'C'],

      
'B': ['C', 'D'],

      
'C': ['D'],

      
'D': ['C'],

      
'E': ['F'],

      
'F': ['C']}



找到一条路径：  
 

def find_path(graph, start, end, path=[]):

    path = path
[start]

    if start ==
end:

     
return path

    if not
graph.has_key(start):

     
return None

    for node in
graph[start]:

     
if node not in path:

       
newpath = find_path(graph, node, end, path)

       
if newpath: return newpath

    return
None



找到所有路径：  
 

def find_all_paths(graph, start, end, path=[]):

    path = path
[start]

    if start ==
end:

     
return [path]

    if not
graph.has_key(start):

     
return []

    paths =
[]

    for node in
graph[start]:

     
if node not in path:

       
newpaths = find_all_paths(graph, node, end, path)

       
for newpath in newpaths:

         
paths.append(newpath)

    return
paths



找到最短路径：  
 

def find_shortest_path(graph, start, end, path=[]):

    path = path
[start]

    if start ==
end:

     
return path

    if not
graph.has_key(start):

     
return None

    shortest =
None

    for node in
graph[start]:

     
if node not in path:

       
newpath = find_shortest_path(graph, node, end, path)

       
if newpath:

         
if not shortest or len(newpath) <
len(shortest):

           
shortest = newpath

    return
shortest



希望本文所述对大家的Python程序设计有所帮助。