数据结构与算法(Python版)五十九：图抽象数据类型的Python实现

ADT Graph的实现：实例

ADT Graph的实现：顶点Vertex类

Vertex包含了顶点信息， 以及顶点连接边信息

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

    def addNeighbor(self, nbr, weight=0):
        # nbr是顶点对象的key
        self.connectedTo[nbr] = weight

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

    def getConnections(self):
        return self.connectedTo.keys()

    def getId(self):
        return self.id

    def getWeight(self, nbr):
        return self.connectedTo[nbr]

ADT Graph的实现：图Graph类

Graph保存了包含所有顶点的主表

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

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

    def getVertex(self, n):
        if n in self.vertList:
            # 通过key查找顶点
            return self.vertList[n]
        else:
            return None

    def __contains__(self, n):
        return n in self.vertList
    
    def addEdge(self, f, t, cost=0):
	    if f not in self.vertList:
	        # 不存在的顶点先添加
	        nv = self.addVertex(f)
	    if t not in self.vertList:
	        nv = self.addVertex(t)
	    # 调用起始顶点的方法添加邻接边
	    self.vertList[f].addNeighbor(self.vertList[t], cost)

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

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