Description

Submission

class Solution {
    void dfs(vector<vector<int>>& next, int cur, vector<bool>& visited) {
        if(visited[cur]) return;
        visited[cur] = true;
        for(auto i: next[cur]) {
            dfs(next, i, visited);
        }
    }
public:
    int countComponents(int n, vector<vector<int>>& edges) {
        vector<vector<int>> next(n);
        vector<bool> visited(n, false);

        for(auto e: edges) {
            next[e[0]].push_back(e[1]);
            next[e[1]].push_back(e[0]);
        }

        int ret = 0;
        for(int i = 0; i < n; ++i) {
            if(!visited[i]) {
                dfs(next, i, visited);
                ret++;
            }
        }

        return ret;
    }
};