from collections import defaultdict
 
class Graph:
    def __init__(self, num_vertices):
        self.graph = defaultdict(list)
        self.num_vertices = num_vertices
 
    def add_edge(self, u, v):
        self.graph[u].append(v)
 
    def topological_sort_util(self, v, visited, stack):
        visited[v] = True
 
        for i in self.graph[v]:
            if visited[i] == False:
                self.topological_sort_util(i, visited, stack)
 
        stack.append(v)
 
    def topological_sort(self):
        visited = [False] * self.num_vertices
        stack = []
 
        for i in range(self.num_vertices):
            if visited[i] == False:
                self.topological_sort_util(i, visited, stack)
 
        sorted_list = []
        while stack:
            sorted_list.append(stack.pop())
 
        return sorted_list
 
# 测试代码
g = Graph(6)
g.add_edge(5, 2)
g.add_edge(5, 0)
g.add_edge(4, 0)
g.add_edge(4, 1)
g.add_edge(2, 3)
g.add_edge(3, 1)
 
sorted_list = g.topological_sort()
print("拓扑排序结果：", sorted_list)