题解在此

并查集题目的广搜代码

#include <bits/stdc++.h>
using namespace std;
vector<int>ve[100010];
bool vis[100010]={};
void bfs(int i){
    queue<int>q;
    q.push(i);
    vis[i]=i;
    while (q.size()){
        int l=q.front();
        q.pop();
        for (auto k:ve[l]){
            if (vis[k]==0){
                vis[k]=1;
                q.push(k);
            }
        }
    }
}
int main(){
    int n,m;
    cin>>n>>m;
    for (int i=1;i<=m;i++){
        int u,v;
        cin>>u>>v;
        ve[u].push_back(v);
        ve[v].push_back(u);
    }
    bfs(1);
    int ans=0;
    for (int i=1;i<=n;i++){
        if (vis[i]==0){
            ans++;
            bfs(i);
        }
    }
    cout<<ans;
    return 0;
}