邻接表的python实现

Vertex类

每个顶点使用字典来跟踪它连接的顶点和每个边的权重。这个字典称为'connectedTo'。

class Vertex:
    def __init__(self,key):
        self.id = key
        self.connectedTo = {}

    #从这个顶点添加一个连接到另一个
    def addNeighbor(self,nbr,weight = 0):
        self.connectedTo[nbr] = weight

    def __str__(self):
        return str(self.id) + 'connectedTo' + str([x.id for x in self.connectedTo])

    #返回邻接表中的所有的项点
    def getConnections(self):
        return  self.connectedTo.keys()

    def getId(self):
        return self.id

    #返回从这个顶点到作为参数顶点的边的权重
    def getweight(self,nbr):
        return  self.connectedTo[nbr]

Graph类

class Graph:
    def __init__(self):
        self.vertList = {}
        self.numVertices = 0

    def addVertex(self,key):
        self.numVertices = self.numVertices + 1
        newVertex = Vertex(key)
        self.vertList[key] = newVertex
        return  newVertex

    def getVertex(self,n):
        if n in self.vertList:
            return  self.vertList[n]
        else:
            return  None

    def __contains__(self, n):
        return  n in self.vertList

    def addEdge(self,f,t,const = 0):
        if f not in self.vertList:
            nv = self.addVertex(f)
        if t not  in self.vertList:
            nv = self.addVertex(t)
        self.vertList[f].addNeighbor(self.vertList[t],const)

    def getVertices(self):
        return  self.vertList.keys()

    def __iter__(self):
        return  iter(self.vertList.values())

测试：

g = Graph()
for i in range(6):
    g.addVertex(i)
print(g.vertList)

输出：

{0: <__main__.Vertex object at 0x000001E42C146518>, 
1: <__main__.Vertex object at 0x000001E42C146550>, 
2: <__main__.Vertex object at 0x000001E42C146588>, 
3: <__main__.Vertex object at 0x000001E42C1465C0>, 
4: <__main__.Vertex object at 0x000001E42C1465F8>, 
5: <__main__.Vertex object at 0x000001E42C146630>}

g.addEdge(0,1,5)
g.addEdge(0,5,2)
g.addEdge(1,2,4)
g.addEdge(2,3,9)
g.addEdge(3, 4, 7)
g.addEdge(3,5,3)
g.addEdge(4,0,1)
g.addEdge(5,4,8)
g.addEdge(5,2,1)

for v in g:
    for w in v.getConnections():
        print("( %s , %s )" % (v.getId(), w.getId()))

输出：

( 0 , 5 )
( 0 , 1 )
( 1 , 2 )
( 2 , 3 )
( 3 , 5 )
( 3 , 4 )
( 4 , 0 )
( 5 , 2 )
( 5 , 4 )