leetcode-323 Number of Connected Components in Undirected Graph

# Given n nodes and list of edges, return number of connected components.

class Solution:
    def countComponents(self, n: int, edges: List[List[int]]) -> int:
        parent = list(range(n))

        def find(x):
            if parent[x] != x:
                parent[x] = find(parent[x])
            return parent[x]

        def union(x, y):
            root_x, root_y = find(x), find(y)
            if root_x != root_y:
                parent[root_x] = root_y
                return True
            return False

        components = n
        for x, y in edges:
            if union(x, y):
                components -= 1

        return components

# Time: O(E * α(N)), Space: O(N)
# AirBnB: Tests union-find understanding