机器学习——最短路径算法_基于机器学习的最短路径搜索系统

理论

使用字典的方式构建有向图，并搜索图中的路径。
提供了三种不同的操作函数：
不足点：只能够处理无权无向图

代码实现

#这个图有6个节点(A-G)和8个弧。它可以通过下面的Python数据结构来表示：
graph = {'A': ['B', 'C','D'],
         'B': ['E'],
         'C': ['D','F'],
         'D': ['B','E','G'],
         'E': [],
         'F': ['D','G'],
         'G': ['E']}
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# 找到一条从start到end的路径
def findPath(graph,start,end,path=[]):   
    path = path + [start]
    if start == end:
        return path 
    for node in graph[start]:
        if node not in path:
            newpath = findPath(graph,node,end,path)
            if newpath:
                return newpath
    return None
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# 找到所有从start到end的路径
def findAllPath(graph,start,end,path=[]):
    path = path +[start]
    if start == end:
        return [path]
 
    paths = [] #存储所有路径    
    for node in graph[start]:
        if node not in path:
            newpaths = findAllPath(graph,node,end,path) 
            for newpath in newpaths:
                paths.append(newpath)
    return paths
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# 查找最短路径
def findShortestPath(graph,start,end,path=[]):
    path = path +[start]
    if start == end:
        return path
    
    shortestPath = []
    for node in graph[start]:
        if node not in path:
            newpath = findShortestPath(graph,node,end,path)
            if newpath:
                if not shortestPath or len(newpath)<len(shortestPath):
                    shortestPath = newpath
    return shortestPath
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onepath = findPath(graph,'A','G')
print('一条路径:',onepath)
 
allpath = findAllPath(graph,'A','G')
print('\n所有路径：',allpath)
 
shortpath = findShortestPath(graph,'A','G')
print('\n最短路径：',shortpath)
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