深度優先遍歷

深度優先遍歷顧名思義就是一條路走到黑，如圖所示，從0開始遍歷，遍歷他的鄰邊1，當遍歷1時，發現他的鄰邊0已經遍歷了，所以這條路已經走到頭了，所以回過頭來遍歷2。

整個遍歷的順序如下：

使用深度優先遍歷，檢視圖有多少個連通分量。

class ComponentsCounter(object):
    def __init__(self,aGraph):
        self.graph = aGraph
        self.result = 0 #store the number of component
        self.calc()

    def
 
 calc(self):
        for vertex in self.graph:
            vertex.setVisited(False) #let all the vertex being not visited
        for vertex in self.graph:
            if not vertex.getVisited(): #using dfs scan all the vertex that is not visited
                self._dfs(vertex,self.graph.getCCount())
                self.graph.setCCount(self.graph.getCCount() + 1
 
)
                self.result += 1 #done,we need to plus 1

    def _dfs(self,startVertex,ccount):
        startVertex.setCCID(ccount) 
        #we can use id to check whether the two vertices was the same component or not.
        startVertex.setVisited(True)
        for nextVertex in startVertex.getConnections():
            if
 
 not nextVertex.getVisited():
                self._dfs(nextVertex,ccount)

    def getResult(self):
        return self.result