def DFSSearchInner(self, u, explored_list):
    explored_list[u] = True
    self.cache.append(u)
    for v in self.graph[u]:
        if (not explored_list[v]):
            self.DFSSearchInner(v, explored_list)
def DFSSearchInner(self, u, explored_list):
    explored_list[u] = True
    self.cache.append(u)
    for v in self.graph[u]:
        if (not explored_list[v]):
            self.DFSSearchInner(v, explored_list)