algospot - gallery

//알고스팟 - GALLERY
 
#include <iostream>
#include <vector>
using namespace std;
 
int V, E;
vector<vector<int>> adj;
vector<bool> discovered;
int ans;
 
void init()
{
    ans = 0;
    cin >> V >> E;
    adj = vector<vector<int>>(V);
    discovered = vector<bool>(V, false);
    int x, y;
    for (int i = 0; i < E; i++)
    {
        cin >> x >> y;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
}
 
//2:cctv 1:watch 0:none
int dfs(int here, bool isRoot)
{
    discovered[here] = true;
    int there;
    bool isC = false;
    int ret = 0;
    int size = adj[here].size();
    if(isRoot && !size) return 0;
    for (int i = 0; i < size; i++)
    {
        there = adj[here][i];
        if (!discovered[there])
        {
            int flag = dfs(there, false);
            if (!flag)
                isC = true;
            else if (flag == 2)
                ret = 1;
        }
    }
    if (isC)
    {
        ++ans;
        ret = 2;
    }
    return ret;
}
 
void dfsAll()
{
    for (int i = 0; i < V; i++)
        if (!discovered[i])
            if(!dfs(i, true))
                ++ans;
}
 
int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    int C;
    cin >> C;
    for (int t_num = 0; t_num < C; t_num++)
    {
        init();
        dfsAll();
        cout << ans << endl;
    }
}