[Swift]LeetCode323. 无向图中的连通区域的个数 $ Number of Connected Components in an Undirected Graph

Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to find the number of connected components in an undirected graph.Given n nodes labeled from 0 to n - 1 and a lis