图算法之广度优先遍历


class Graph(object):
    def __init__(self):
        self.nodeNeighbors={}#使用邻街表方式表示图
        self.visited={}
 
    def addNode(self,node):#单个添加节点
        if node not in self.nodeNeighbors.keys():
            self.nodeNeighbors[node]=[]
 
    def addNodes(self,*nodelist):#批量添加节点
        for node in nodelist:
            self.addNode(node)
 
    def addEdge(self,edge,var=1):#使用邻街表方式添加图(有向有权图)
        u,v=edge
        if u==v:
            return None
        if v not in self.nodeNeighbors[u]:
            self.nodeNeighbors[u].append([v,var])
            return 1
 
    def nodes(self):
        return self.nodeNeighbors.keys()
 
    def breathFirstSearch(self,root=None):#广度优先遍历算法
        queue=[]
        order=[]
        def bfs():
            while len(queue)>0:
                node=queue.pop(0)
                self.visited[node] = 1
                for n,v in self.nodeNeighbors[node]:
                    if n not in self.visited and n not in order:
                        queue.append(n)
                        order.append(n)
        if root:
            queue.append(root)
            order.append(root)
            bfs()
            for node in self.nodes():#如果节点未遍历完全重新遍历一遍节点 全部检查一遍
                if node not in self.visited:
                    queue.append(node)
                    order.append(node)
                    bfs()
        return order
 
if __name__=="__main__":
    g=Graph()
    g.addNodes(1,2,3,4,5)
    g.addEdge((1,2))
    g.addEdge((1,3))
    g.addEdge((1,5))
    g.addEdge((3,4))
    print g.breathFirstSearch(3)


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