Bus lines

#include <iostream>
#include <vector>
#include <stack>
#include <queue>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <unordered_set>
#include <stdio.h>
#include <string.h>
#include <unordered_map>
#include <fstream>
#include <set>
#include <map>

#define MOD 1000000007
#define ll long long
#define N (1<<50)
#define float double
#define str string

using namespace std;

int m[100001];
int s[100001];
int comp;

void lol(){
    for(int i=0; i<100001; i++)
        m[i]=i,s[i]=1;
}

int root(int a){
    while(m[a]!=a)
        a=m[a];
    return a;
}

void un(int a, int b){
    a=root(a),b=root(b);

    if(a==b)
        return;

    comp--;
    if(s[a]<s[b])
        m[a]=b,s[b]+=s[a];
    else
        m[b]=a,s[a]+=s[b];
}

int l[100000],r[100000];

int main(){
    int n,m,k;
    cin>>n>>m>>k;
    lol();
    comp=n;


    for(int i=0; i<m; i++)
        cin>>l[i]>>r[i],r[i]--,l[i]--;

    vector<int> poist;
    set<int> onko;

    for(int i=0; i<k; i++){
        int a;
        cin>>a;
        a--;
        onko.insert(a);
        poist.push_back(a);
    }
    stack<int> v;
    for(int i=0; i<m; i++){
        if(!onko.count(i)){
            un(l[i],r[i]);
        }
    }
    for(int i=poist.size()-1; i>=0; i--){
        v.push(comp);
        un(l[poist[i]],r[poist[i]]);
    }

    while(v.size()){
        cout<<v.top()<<" ";
        v.pop();
    }
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED