并查集

/*
 *  @filename:~/Documents/workspace/vscode_space
 *  @author: Ly_boy
 *  @date: 2025-04-10 14:47:51  星期四
 *  @compiler: 2025 by Ly_boy, All Rights Reserved.
 */
#include <bits/stdc++.h>

#define endl "\n"
#define debug freopen("in.txt", "r", stdin), freopen("out.txt", "w", stdout)
using namespace std;

int t, n, m, p, u, v, fa[5005]; // n:点数 m:关系 p:询问 u,v:边的两个端点 fa:并查集数组

int find(int x) // 查找x的根节点
{
    if (x == fa[x])
        return x;
    return fa[x] = find(fa[x]);
}

void union1(int x, int y) // 合并x,y两个集合
{
    int fx = find(x), fy = find(y);
    if (fx != fy)
        fa[fx] = fy;
}

void solve()
{
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; i++)
        fa[i] = i; // 初始化并查集
    for (int i = 1; i <= m; i++)
    {
        scanf("%d%d", &u, &v);
        union1(u, v); // 合并u,v两个点
    }
    int cnt = 0;
    for (int i = 1; i <= n; i++)
        if (fa[i] == i)
            cnt++; // 统计集合个数
    printf("%d\n", cnt);
}

int main()
{
    scanf("%d", &t);
    while (t--)
        solve();
    return 0;
}