class Solution:
    def solve(self, friends):
        nodes = len(friends)
        visited = [False for _ in range(nodes)]
        ans = 0
        def dfs(vertex, visited): 
            visited[vertex] = True
            for nei in friends[vertex]:
                if not visited[nei]:
                    dfs(nei, visited)
        for i in range(nodes):
            if not visited[i]:
                dfs(i, visited)
                ans += 1
        return ans
ob = Solution()
friends = [[0, 1, 5], [1, 0], [2], [3, 4], [4, 3], [5, 0]]
print(ob.solve(friends))

[[0, 1, 5],
[1, 0],
[2],
[3, 4],
[4, 3],
[5, 0]
]

3