0323-number-of-connected-components-in-an-undirected-graph.py

class UnionFind:
    def __init__(self):
        self.f = {}

    def findParent(self, x):
        y = self.f.get(x, x)
        if x != y:
            y = self.f[x] = self.findParent(y)
        return y

    def union(self, x, y):
        self.f[self.findParent(x)] = self.findParent(y)


class Solution:
    def countComponents(self, n: int, edges: List[List[int]]) -> int:
        dsu = UnionFind()
        for a, b in edges:
            dsu.union(a, b)
        return len(set(dsu.findParent(x) for x in range(n)))