题目：

题解：

func findCircleNum(isConnected [][]int) (ans int) {n := len(isConnected)parent := make([]int, n)for i := range parent {parent[i] = i}var find func(int) intfind = func(x int) int {if parent[x] != x {parent[x] = find(parent[x])}return parent[x]}union := func(from, to int) {parent[find(from)] = find(to)}for i, row := range isConnected {for j := i + 1; j < n; j++ {if row[j] == 1 {union(i, j)}}}for i, p := range parent {if i == p {ans++}}return
}