球迷

版权声明：wywwzjj https://blog.csdn.net/weixin_42348709/article/details/84312185

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;

int pa[N];

int findRoot(int x) {
    return pa[x] != x ? pa[x] = findRoot(pa[x]) : x;
}

void Union(int x, int y) {
    int a = findRoot(x);
    int b = findRoot(y);
    pa[a] = b;
}

int main(){
    ios::sync_with_stdio(0);cin.tie(0);
    //freopen("D:\\i.txt","r",stdin);
    int n, m; cin>>n>>m;
    for(int i=1;i<=n;i++) pa[i] = i;
    int x, y;
    while(m--) {
       cin>>x>>y;
       Union(x, y);
    }
    for(int i=1;i<=n;i++) findRoot(i);
    set<int> st;
    for(int i=1;i<=n;i++)
        st.insert(pa[i]);
    cout<<st.size()<<endl;
    return 0;
}