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  • python数据结构之图的实现

    python数据结构之图的实现,官方有一篇文章介绍,http://www.python.org/doc/essays/graphs.html

    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
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  • 原文地址:https://www.cnblogs.com/yupeng/p/3414569.html
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