ConnectedComponents.cpp

#include <bits/stdc++.h>
using namespace std;

int n;

void mark_connections(vector<int>array[],int*check,int k){
    check[k] = true;

    for(int i : array[k]){
        if(check[i])continue;
        mark_connections(array,check,i);
    }
}

int solve(vector<int>array[],int*check,int n){

    int ans = 0;
    for(int i = 0 ; i < n ; i ++){
        if(check[i])continue;
        else{ans++;}
        mark_connections(array,check,i);
    }

    return ans;

}

int main(){
    int m;
    cin >> n >> m;


    vector<int>array[n];
    int check[n];

    for(int i = 0 ; i < n ; i ++)check[i] = 0;
    
    for(int i = 0 ; i < m ; i ++){
        int x,y;
        cin >> x >> y;

        array[x-1].push_back(y-1);
        array[y-1].push_back(x-1);
    }

    int a = solve(array,check,n);

    cout << a;
    return 0;
}