python数据结构之图的实现方法

本文实例讲述了python/' target='_blank'>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。